Customers who have purchased music from Microsoft's now-defunct MSN Music store are now facing a decision they never anticipated making: commit to which computers (and OS) they want to authorize forever, or give up access to the music they paid for. Why? Because Microsoft has decided that it's done supporting the service and will be turning off the MSN Music license servers by the end of this summer.

MSN Entertainment and Video Services general manager Rob Bennett sent out an e-mail this afternoon to customers, advising them to make any and all authorizations or deauthorizations before August 31. "As of August 31, 2008, we will no longer be able to support the retrieval of license keys for the songs you purchased from MSN Music or the authorization of additional computers," reads the e-mail seen by Ars. "You will need to obtain a license key for each of your songs downloaded from MSN Music on any new computer, and you must do so before August 31, 2008. If you attempt to transfer your songs to additional computers after August 31, 2008, those songs will not successfully play."

This doesn't just apply to the five different computers that PlaysForSure allows users to authorize, it also applies to operating systems on the same machine (users need to reauthorize a machine after they upgrade from Windows XP to Windows Vista, for example). Once September rolls around, users are committed to whatever five machines they may have authorized—along with whatever OS they are running.

The news will likely upset a number of Microsoft's customers, who bought music from MSN Music before the company launched the Zune Marketplace and decided to ditch the old store. Microsoft's decision to turn off the MSN Music authorization servers serves as a painful reminder that DRM ultimately severely limits your rights. Companies that control various DRM schemes, as well as the content providers themselves, can yank your ability to play the content which you lawfully purchased (and now, videos) at any moment—no matter what your expectation was when you bought it. Some Major League Baseball fans learned this the hard way last fall.

Bennett insists that MSN Music keys are, in fact, not yet expiring. Technically speaking, that's true—if I authorize one of my PCs, never get rid of it for the rest of my life, and never upgrade its OS, I will be able to play my tracks forever. But as some of our readers note, this technicality is not rooted in reality—the authorizations will now expire when the computer does, for whatever reason. DRM-free music may be the new hotness these days, but people who bought music before the record industry began to see the light are still stuck with their DRMed music.

Of course, MSN Music customers do have one other option: burning all of their music to audio CD and then re-ripping them back to the computer as MP3s, sans DRM. But that's a lossy, lousy solution.