I just ran into this last night on an upgrade to 4.1.40. It turns out to solve it you need to stop the keyserver service. Then go to folder for IP Office, Then Keyserve, then drivers, double-click on setupx86, Click Functions, choose install sentinal driver, ERASE the \I386 from the end of it and click ok. This will properly install the sentinal driver. Then restart the keyserver service. The licenses should then become valid and stay that way.
If not, you may have to go to add/remove programs, modify your admin suite to remove the keyserver. Then add the sentinal driver as above. Then re-add keyserver through add/remove programs. Make sure you start the service for keyserver when finished.