Witcher 2 had DRM for about 48hrs, and then the developers removed it because it was hurting legitimate customers.
It was an awkward situation. CD Projeckt (a publisher, and the parent company of CD Projekt RED) distributed The Witcher 2 in Poland and internationally through GOG.com. But they needed the help of international publishers to sell retail in other parts of the world, so they signed up with Bandai Namco and Atari to publish the game elsewhere. (Apparently Polish laws make it nearly impossible for them to handle international distribution themselves, which is the main reason they registered their subsidiary, GOG.com, outside Poland)
Anyway, although CD Projekt is firmly anti-DRM, one or both of these other publishers decided to slap DRM onto the files that they distributed, more because of internal policy than any practical reason. The DRM broke the game and made CD Projekt look like hypocrites, so they quickly released a patch to repair all the files broken by the DRM, which inevitably disabled the DRM in the process. I believe the publishers who broke the game sued them for fixing it, but CDP won that case. Unfortunately Bandai Namco won another lawsuit forcing CDP to make the game more expensive for Australians instead of making it the same price everywhere.
If you bought The Witcher 2 from GOG it never had DRM in the first place, and no matter where you bought the game you could go to gog.com/witcher/backup to redeem a complimentary GOG version for yourself.