To move your license to other system you need to deactivate your activation code from the active system, then reactivate it on the destination system.
If you have access to the active system, the best way to deactivate your code is using the SGOActivationTool. This tool permits to deactivate and reactivate activation codes in an easy way.
Also, if you go to SGOActivationTool->Advanced mode then you will see a listing with all your licenses and all your computers, and you can simply drag and drop licenses between any computers that you have previously used. That's all that you need to do for a license reallocation.
If you do not have access to a particular system anymore (broken system, etc) then you can deactivate your code in your SGO web account -> Actvation codes.
Alternatively, please note that you do not need to reallocate licenses if the systems are connected in a network: All Mistika licenses are "floating licenses", which means that if a licensed system is already available in your network then you can simply select it in the SGOActivationTool->license server field in any other computer, or in the license dialog appearing when opening the application. (nothing needs to be done in the server side, just tell the ip of the license server to the client computer, using the license server settings wheel icon). Later, the license will be returned to the server as soon as the client computer closes the application.
For example, you can assign several activation codes to a same license server (a same computer) and then get them from any other clients at any time, if you prefer to work in this manner.
instructions about how to configure a remote license server can be found here:
https://support.sgo.es/support/solutions/articles/1000261513-how-to-configure-a-floating-license
During all this process, please note that "activation codes" and "license keys" are different things. The "activation code" is what you purchase and it is generic (it permits to get a "license key" for any computer, but only one at a time ) . Later, when the activation code is unassigned from that computer then the existing license key will not work anymore, and you can use the activation code to generate a license key for the next computer.
The activation codes are sent by email at purchase time, but you can also find them in your web account: https://www.sgo.es/my-account/ . You can also use your shop account to manage licenses directly in there.
Normally you only use the activation codes and the license keys are managed automatically. But if you need to obtain licenses manually with no internet connection you can also do it in your SGO website account. In that case you will be asked for the LMData identifier of the computer, which you can get with SGOActivationTool->Advanced Mode->AddActivationCode