Try to uninstall and reinstall.
The licensing system is timestamped. Set your date back to the old time, uninstall, set the date correctly, then re-install. However, it may not work anymore, as once the licensing system things it has gone beyond the 30 day mark, it will lock the licensing file and thereafter it can only be unlocked by using a valid serial.
I think you're SOL. Adobe makes unbelievably crappy installer and updater programs, but their demo software is thorough and incredibly hard to spoof.