This has nothing to do with DRM, it is a crappily designed customer authentication system. If B&N had any sense they would offer customers the ability to redownload their purchases at any time after say, 120 days, for an additional 25c.
People can redownload their purchases at any time for 0 cents, whether it's 120 days or 3 years later. They just need to have a current credit card on file. Question the wisdom of that if you will, but there's absolutely no recharging people or disabling of access.
