The Atari Forums have an "explanation" of the DRM in The Chronicles of Riddick: Assault on Dark Athena, focusing on why DRM is used and their three activation limit that is the focus of many objections (thanks Voodoo Extreme). The post points out that people do actually attempt to pirate games (they say one activation key has been tried over 50,000 times), but they feel their limits suit most users, in "only about 10% of all the Riddick PC games sold have been activated more than once." The post conclude with these reassurances:

DRM is not designed to keep you from playing the game, nor is it designed to combat any after market sales. After market sales for PC games are nowhere near what they are for console games anyway, aside from ebay, craigslist and yard sales I can’t even really think of anywhere to get used PC games.

I want to make it clear that there are people who are monitoring activations so if and when we get into an issue with people not being able to play that issue will be addressed. Should the case get so severe it effects a large portion of the gamers, more activations will be set in place as needed. Further down the line the DRM will be removed and a new unprotected exe will be released.

So to summarize if you buy Riddick legally on the PC we are going to do our best to make sure you can play it for as long as you want. I hope this helps answer some of your questions / concerns.