The thing is, your system really isn't DRM.
Despite the words the letters stand for, DRM have always been described (and sold to greedy and technically clueless managers and CEO) as a way to control precisely how their customers could and, more to the point, could not use whatever it was they "bought".
I may look like I'm nitpicking on words, but it's important to make that clear. Whereas your system can only be cracked through general purpose hacking (i.e. breaking into your server), DRM can, in essence, only work if you put a cop behind everyone's shoulder.
I don't know about you, but if we get to that kind of extreme I'd like to at least be spared the cost of the DRM itself...
