I think that the problem here is to get the current date. For that you should read
this[
^] by SeaWater to get the date from a remote server.
If you can not get this date, you should not load the application.
Then, depending on you own logic compare this date to an "expiration" date you established.
As an alternative, you could enable the user to open the aplication for a limited number of times...
Best regards