The receipt Apple returns from a purchase does not include the iTunes account information of the user that purchased the content and there also doesn't seem to be way of having Apple verify if a given device UUID belongs to an iTunes account.
Is there anyway to implement a secure DRM system that allows users to purchase content once and be able to use the content for all on all the devices associated with their iTunes account?
If there's a way to replay a receipt or spoof information, I don't consider it a secure DRM system.
This question, and subsequently, my answer and its comments, sparked my curiosity about this.
No.