If the system date was tampered and the check for system date modification was enabled using CheckSysdateChanged or SysdateChanged you can use any Activation Key to unlock the version - e.g. a key which sets Demoversion to true or a key without any settings.

 

Before the activation key is applied the user has to turn back the date to today's date. The activation key resets the internal date check using this date as the new date to start testing again.