Copying info from this doc: http://helpx.adobe.com/x-productkb/global/trial-software-expired-early.html
Adobe trial software is time limited, and otherwise has the same feature set as the licensed version. Some scenarios can cause trial software to expire early:
- Changing the system clock
- Modifying the executable file
- Attaching a debugger
- Automated virus scans
Trial periods can't be extended. After a trial expires, you need a serial number to install the software as a licensed version. Or, you can install trial software on another computer.
But I did not do any of those things. I"m not asking that the trial period be extended -- just that it start and work.
It can't be done. Whatever happened has locked the licensing system and as much as this may suck, only inputting a serial number can release it again. We won't speculate as to why it happened, it could after all be a technical glitch, but that's just how it is. If you have a secondfary computer, try it there. Or you could make a leap of faith and just buy it...