System Dates - Evaluation Program

I wish to create an application that runs like the evaluation notices that appear on programs.
I want my system to select a date when the app is first run, then count up to 30 days to get the expiry date.
The system will then check every day if the 30 days is up and if not show the remaining days until lock out.
When 30 days are up, the system will make all objects invisible until the user enters a Serial Key.
I think a registry write is required but Im not sure on how to proceed.

Any help here would be very grateful and a point increase may be in order.

Thanks
Scott