hi,
Create a password Protected access database, Save Installation Date and End date.
In program Check for:
If System date> enddate or
systemdate> (installationdate)+30 then
Give message and end the program.
Here u have to be carefull, In case user changes the Systemdate and can continue using it.
It is always a Good Option to check for Number Of Tries.. Say for 1000, Keep a Counter , Increment everytime the user Logs In, if it crosses 1000 end the program with alert.
Regards'
Veena