Protected application is tracking system date and time (system clock) on each run.

In case system clock on computer has been set back (and the change is outside of "Allowed system time adjustments" period) protected application will consider system time as invalid.

Two things could happen at this point:

If "Reset license in case of invalid system time" option is enabled, application will reset license, display error message and will ask for new activation code.

If "Reset license in case of invalid system time" option is disabled, application will just display warning message (Demo_SystemTime_Error: 'System date/time error! Please correct your system date/time') and exit. End user has to correct system time (by setting it ahead of last recorded system time) in order to be able to enter protected application again. If this is not possible, new update protected with "Reset license in case of invalid system time" option enabled will reset license due to invalid system time and ask for new activation code.

Knowledge base
PC Guard: Remote protection