Cocoa Programming for OS X: The Big Nerd Ranch Guide
by Aaron Hillegass, Adam Preble, Nate Chandler
Receipt Validation
Mac App Store apps differ from iOS apps in one key area, however: There is no OS support for license checking. That is, without special effort on your part, there is no copy protection. If copy protection is important to you, you will need to implement receipt validation.
When purchased from the Mac App Store, an application is downloaded to the user’s system. A file containing the application receipt will be placed in the application bundle. The receipt contains the application’s bundle identifier, its version string, and a hash of the computer’s GUID. Receipts are cryptographically signed by Apple.
By verifying the information in this receipt, your application can determine whether it is authorized to run on ...