Written for Synergy 3 (v3.7.2) and Synergy 1 (v1.21.4), checked 4 October 2026.
Your license is activated on each computer you use as a server in Synergy 1, or as the primary computer in Synergy 3. Most licenses activate online, automatically. Licenses with an offline serial key activate with a short code exchange instead, for computers on offline or air-gapped networks.
Every computer in your setup still needs your serial key entered, even though only the server or primary computer uses an activation. For the steps in Synergy 3, see: Entering or changing your serial key
For Synergy 1, see: Entering or changing your serial key
Activation limit
Each license has an activation limit: the number of server computers it can be activated on. By default it's 2 for each seat on the license, so a personal license (one seat) can be active on 2 server computers at once. Offline activations have the same limit as online ones. Client computers in Synergy 1 and secondary computers in Synergy 3 never use an activation.
Need more activations? Contact our support team and we'll raise your limit, at no extra cost: Contact support
Once your limit is raised, click Start in the Synergy 1 window on the server computer. In Synergy 3 on the primary computer, click Continue if the activation message is still showing, then click the button at the bottom of the left sidebar (while sharing is stopped, its tooltip reads Paused). That activates your license; you don't need to enter your serial key again.
Using an offline serial key? A raised limit lets more computers activate. Activate each new one under Activate offline computer on your account page, as described under Offline activation below.
Need two separate setups?
For business and enterprise customers: give each setup its own Synergy 3 serial key, or use Synergy 1, which your Synergy Business license includes. For a serial key for each setup, contact our business team: Contact our business team
In Synergy 1, one license can run several separate setups, with each server computer using one activation. If you need more activations, contact our support team and we'll raise your limit, at no extra cost: Contact support
For personal, non-commercial customers: you'll need a second serial key for the second setup, so that each setup has its own. Contact us and we'll help you get one: Contact support
Have Synergy 1 too? Run Synergy 1 on one of the setups instead, with no second license needed. Your Synergy 3 license includes Synergy 1; if it isn't on your account page yet, contact us and we'll add it: Contact support
The reason is how Synergy 3 finds your computers: every Synergy 3 computer with the same serial key finds the others on your network and joins one Screen layout, with one primary computer sharing its keyboard and mouse. So two setups on the same network that use one Synergy 3 serial key become one setup. Synergy 1 doesn't look for other computers; each client connects only to the server you name, so setups don't join each other.
Online activation
Enter your serial key in Synergy 1 on every computer, or in Synergy 3 either enter your serial key or log in to your account. Entering the key or logging in doesn't use an activation. Your license activates automatically the next time Synergy 1 starts as a server, or when a Synergy 3 primary computer starts sharing, using one activation.
For the steps in Synergy 1, see: Entering or changing your serial key
For Synergy 3, see: Entering or changing your serial key
Swapping which computer is in control? You don't use an extra activation. When you make a different computer primary in Synergy 3, or switch the old server to client mode in Synergy 1, the old one gives its activation back as soon as it starts as a client. A computer you've stopped using (or can't start any more) keeps its activation until you deactivate it; activations don't expire on their own.
Reached your limit? Free up an activation yourself by deactivating a computer you no longer use, or ask our support team to raise your limit: Contact support
Either way, click Start in Synergy 1 on the server computer, or the Paused button at the bottom of the left sidebar in Synergy 3 on the primary computer, and it activates without you entering your serial key again.
To deactivate a computer:
- Sign in to your account page.
- In Licenses, click Manage activations next to your license.
- In Activated computers, find the computer by its Activation ID, Computer and Version, and click Deactivate, then confirm with Deactivate computer.
The activation is freed straight away. If that computer later starts as a server again, it uses a new activation. Last seen shows when the computer last contacted us, which for a personal license is usually when it activated, not when it was last used.
Offline activation
With an offline serial key, Synergy 1 and Synergy 3 show an activation code (in the form XXXX-XXXX-XXXX) when they need to be activated. You exchange this for a response code on your account page, from any device with internet access.
In Synergy 3 you can paste an offline serial key, or log in to your account to fetch it, as with any other key. Either way, the computer activates with the code exchange below.
Each computer has its own activation code. The code is unique to that computer, so a response code only works on the computer whose activation code you entered. To activate several computers, repeat these steps on each one, using the activation code shown on that computer.
- On the computer you're activating, start Synergy 1 as a server, or start sharing on the primary computer in Synergy 3. The activation code appears at that point (in Synergy 1, in the Offline activation window), not straight after you enter the serial key.
- On any device with internet access, sign in to your account page.
- Under your license, click Activate offline computer.
- Enter the activation code shown in Synergy 1 or Synergy 3 and click Get response code.
- Back in Synergy 1 or Synergy 3, type the response code into the Response code box and click Activate.
To activate more computers, click Activate another computer in the same window and enter the activation code from the next computer. Don't reuse a code from another computer; it won't work.
Need more offline activations?
Click Request more activations in the Offline activation window on your account page, or contact our support team, and we'll raise your activation limit, at no extra cost: Contact support
Once it's raised, activate each new computer under Activate offline computer, as above. Computers you've already activated stay activated and don't need activating again.
Raising the limit is how extra offline activations work: an offline activation stays counted once its response code is issued, so it can't be deactivated from the account page the way an online one can.
Reactivating a computer you've already activated (for example after reinstalling Synergy 1 or Synergy 3) shows the same activation code and doesn't use another activation, even if you've reached your limit.
After you get a response code, the account page shows how many offline activations you've used (for example, Offline activations used: 2 of 3).
Switching to an offline serial key
If you have a personal license, you can switch it to an offline serial key yourself. Your old serial key stops working as soon as you switch, so you'll need to enter the new one on each of your computers.
- On your account page, click Request an offline serial key under your license.
- Confirm by clicking Switch to an offline serial key.
- Enter the new serial key in Synergy 1 or Synergy 3 on each of your computers. In Synergy 3, logging in to your account fetches the new key for you.
For the steps in Synergy 1, see: Entering or changing your serial key
For Synergy 3, see: Entering or changing your serial key
Have a business license? Our support team can switch it to an offline serial key for you: Contact support
Want online activation back?
Contact our support team and we'll move your license back to online activation: Contact support
You can't switch back yourself, because the account page only switches a license to an offline key. Switching replaced your old license with a new one, and the offline activations you've already used stay counted against your activation limit.
Troubleshooting
Messages in Synergy 1 or Synergy 3
- That response code is not valid for this computer. Check you typed the response code exactly, and that it was generated from the activation code shown on this computer.
- This license has reached its activation limit. Deactivate a computer you no longer use from your account page, or contact support for more activations. Deactivate a computer under Manage activations on your account page, or contact our support team and we'll raise your limit, at no extra cost. Then click Start in Synergy 1 on the server computer, or the Paused button in Synergy 3 on the primary computer, and it activates. To contact our support team: Contact support
- Invalid serial key. Please log in to your Synergy account to get the correct one. (Synergy 3) Copy your serial key again from your account page and paste it in, or log in to your account instead.
- Invalid serial key in a message from Synergy 1. Older versions of Synergy 1 can't read the current serial key format. Update to the latest Synergy 1, or see what to do if you can't, and what each older version shows: Entering or changing your serial key
- Sorry, there was a problem logging in. (Synergy 3) Switch to an offline serial key, which activates without contacting our server, as described under Switching to an offline serial key above. This message shows when the computer can't reach our server to log in, for example because its network blocks it.
- A unique ID for this computer could not be determined, so an activation code cannot be generated. Synergy 1 or Synergy 3 can't generate an activation code on this computer. Please contact our support team: Contact support
Messages on the account page
- That activation code isn't valid. Check it for typos. Check the code was copied exactly from Synergy 1 or Synergy 3.
- This activation code doesn't match any of your offline licenses. Check the activation code was copied exactly from Synergy 1 or Synergy 3, and that you're signed in to the account that owns the license.
- This license has reached its activation limit. (offline serial key) Click Request more activations, or contact our support team, and we'll raise your limit, at no extra cost. Then click Get response code again. To contact our support team: Contact support