Actually he 'rented' the book as well. Some years ago companies all found they could use the TOS against us for digital purchases. His 'purchase' was actually a license to view X content on Y devices Z times.

This enrages me as they charge us money for a virtual good which as soon as we purchase is considered worthless by the selling company. They can ban you- effectively closing your account and blocking your access to your 'purchases', or they can, as discussed here, decide to remove your purchase for 'insert_reason' without making you whole. This incentivizes companies toward hostile consumer attitudes in the name of profit.