Code to prevent access to excel doc after 3 months

We are a publishing company, which among other things, sells a database in an excel file. A small number of our subscribers are Apple users (like me!)

Could anyone suggest an applescript which would set an expiry date on the use of this excel file?

Is there also an applescript which could copy some unique information from the computer (eg username) and save it onto an unseen part of the excel sheet the first time it is opened? Whenever the document is opened the script would then check whether the username is the same, this would prevent the file being opened by more than one person.

I would also be very happy to hear from developers who could do this for me as a commercial project.


I think I could provide a solution through a read only applet, or through a droplet delivered with the Excel sheet
and an install script to install the whole package when the user downloads.
What I can tell you is that the solution won’t be 100% tinker proof, that is if some really resourceful person could
reverse-engineer the compiled run-only part of it, he will bypass the expiry date by getting the password which gives access to now invisibly password protected Excel file.

Best Regards