Typing "REPEAT" as a software key should get you a 30 day extension of the trial.At least, that's the way things used to work. I cannot say with absolute certainty it still works.But if you asked TechSmith themselves by submitting a support ticket.They could tell you for sure.
After that, the software will refuse to boot up.You'll have your recordings, so if you purchase the program you can use Camtasia to edit and produce videos with them.
This is a Free Service...............
Submit a ticket