If you buy media that has Digital Rights Management (DRM) on it you are not actually purchasing it. You are renting it. If the content owner (don't be fooled by this phrase, even though you "bought" the content you do not own it) decides that you have had enough time with your purchase they can pull the plug and everything you bought from them is gone.
What has DRM on it? Well almost any media purchase that is downloaded over the internet (one big name would be iTunes). If you have doubts that a company would disable something that you bought check out this story:
Background: Beginning in 2003, MLB offered fans the chance to download full games to their computer at $3.95 each. When you attempted to open the media file -- either on your hard drive or after it was burned to a CD -- it connected with a MLB.com webpage to obtain a license. Once the license had been verified, the game would play.
At some point during 2006, MLB deleted that essential webpage. Since then, none of the videos that fans purchased will play.
He contacted the MLB customer service and they said:
"MLB no longer supports the DDS system" that it once used and so any CDs with downloaded games on them "are no good. They will not work with the current system."
I was told there is absolutely nothing MLB can do about these lost games. Plus, they said my purchases were all "one-time sales" and thus "there are no refunds".
So just a warning to put out there, if you "purchase" something with DRM on it, you are at the mercy of who you are renting it from, and your investment can be worth nothing whenever they feel like screwing you.