If you did not activate your initial license during the installation process, you can go to the Settings / License tab, then enter the required information and activate your License Key.
If you later get a new license agreement (for example, if you purchased additional Seats), go to the Settings/License tab and click the Update License button. Although the preferred way is to update the license online, there is also an option provided for updating the license offline, for those Servers which cannot gain access to the Internet.
In any case, you can update or restore your License Key with no interruption to your Splashtop Center service. There is no need to restart the service, and the remote user connections currently in session will not be lost/disconnected.
NOTE: The License Key would need to be re-activated if you were to re-install the software someday. This includes situations where you upgrade or clean the installtion of Splashtop Center — you would need to activate the License Key again. Keep in mind that one License Key can be activated up to five times.