Product: Platinum, Gold
Version: 5.x

Description:
The XS-Key shows a different serial number each time I try to launch Logic The program start is then terminated showing an error message "no valid platform authorization".

Explanation:
The XS-Key is inactive

This can be caused by

-faulty system extensions
-defective USB hardware

Solution:
Unplug the XS-Key for a while. It will be reactivated at the next start of Logic.