Fiction

most devices these days have an internal clock that you can't reset. When you do the reset provided to you, it actually only sets the difference between the internal clock and what time should be displayed. The more solid DRM systems use that internal clock.

I kept an old MP3 player long after it was more or less obsolete because it didn't have an internal clock and once I moved a protected audiobook onto it, it would be good until I finished listening. Used if for Shelby Foote's three volume Civil War: A Narrative, 45 hours each. I wasn't nearly committed enough that I was going to finish each in 14 days...