Bypassing questions of whether or not this is truly implementable, this would mean there's a functional expiration date on the file...the time it takes me to go through two computers.
I do question how implementable it is though...it's fairly trivial to do a bit by bit copy.
However, for my purposes it doesn't really matter. If it's not a standard format I'm extremely unlikely to purchase it...needs to be readable on my Linux box as well as Windows.