Joerg,
On my new (Windows 11) notebook Photo Mechanic (Build 6496) forgets the license information every 2 to 4 days!
It is still possible to register me again, but I am afraid that I am using too many licenses.
For a problem like this, I suggest contacting our support folks at:
By email: support@camerabits.com
By phone: +1 503.547.2888
Hours: Mon-Fri, 9:00am-5:00pm [PST/PDT]