Dan,

What I do is devise a formula that calculates an integer based on a date. I then create a file with the expiration date and the corresponding integer. The customer doesn't know the formula, so he can't figure out the right integer to go with a new date. When the app starts it checks the integer against the expiration date and the expiration date against the current date. We just e-mail them a new file to renew.

>I am developing an app for a client who is planing on licensing the program on an annual basis to his customers. I am trying to come up with a way to disable the program automatically when the annual license expires. When the customer renew's his/her license they can be sent a new KEY that can be entered so that the app will run again until the new license expires, and so on.
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>Has anybody devised a reliable method for doing this?