Is there a way to disable a functioning spreadsheet if it is not running on a specific computer? In other words, If I sell the spreadsheet that I have created to a user, I do not want that user to be able to send it to friends and still be usable. Can I code the serial number of the computer into the program and compare it to the serial number of the computer that the spreadsheet is running on and disable the spreadsheet if the two do not match?