Enable receipt validation for the Mac App Store.
This enables receipt validation for the Mac App Store. If this is enabled, your game will
only run when it contains a valid receipt from the Mac App Store. Use this when submitting
games to Apple for publishing on the App Store. This prevents people from running the game
on any computer then the one it was purchased on.
Note that this feature does not implement any strong copy protection. In particular, any potential crack against one Unity game would work against any other Unity content. For this reason, it is recommended that you implement your own receipt validation code on top of this using Unity's plugin feature. However, since Apple requires plugin validation to initially happen before showing the screen setup dialog, you should still enable this check, or Apple might reject your submission.