Where can I find Tom Rettig's cryptor file tool?

>>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?
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>How about using Tom Rettigs cryptor file to store the experation date in? You can ship a new encrypted file also.
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>Another thing you will want to do is store the date the program was last run, and verify that it is always later than the previous run. This will keep the clock changers happy.
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>There is also a copy protection library out there... I used it is a clipper program and it works well. It is called Copy Pro or such. I have seen it at hallogram. It is very easy to use.
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>BOb