DRM license website not found?

Having purchased some WMA song's a couple of years ago when it sits on a NAS server on my network. I have since upgraded my machines several times and now trying to play the purchased songs but it seems that my DRM license is corrupt (as I keep on getting such a message in any media player software I try) and I do not remember the specific website from which I purchased the songs from.

Is there a way of extracting information as to where I purchased songs from on the Internet from the un-playable songs themselves? If the website or audio player is no longer available how can I get Soundtaxi to remove the DRM?

It's so frustrating as I purchased and own audio tracks, I am a competent MCP PC user, no wonder people prefer downloadable MP3s with no DRM!

Any help much appreciated, thank you