The DRM protection can be used in different ways, including having it expire after a designated time period, not work on portable devices, not be copied for mass distribution, etc. While the issue of Fair Use comes up frequently (I purchased the music, so I should be able to do whatever I want with it), circumventing copy protection is illegal here in the United States (see the Digital Millenium Copyright Act for the primary brick wall) and also usually violates the licensing agreement and/or terms of service with the group you purchased the music from. For both reasons, obtaining help in doing such violates the forum policies. (That's the explanation of why it's a forbidden topic.)
If you need the music in an unprotected format, you can contact the company you purchased it from and ask for assistance and/or complain, but you'll rarely get anywhere. They have chosen to protect the music for a reason, and since their terms of service probably state that the music's protected, and thus restricted as to its use, they're under no obligation to help. But, it may be worth a try. This is one of the few reasons that good old-fashioned CDs are still a big seller.
Sorry.
John