So if we were to have installations on 10 pc's, the first two instances that were opened would grab the full license, and the rest would open as express?
I am not sure about that as I lack the experience (as far we never ran out of licenses).
What I know for sure is, that if you point Prime to a bogus licenses server, it will automatically go into Express mode. I don't know what happens if a valid license server is out of licenses but I could imagine that Prime would do the same. maybe someone else can confirm.