I'm not sure if it is really possible to code a whole protection/licencing system with only the marketplace module. I think you got only some kind of licencing stuff there.
About the iLok2 protection scheme, I think nobody has ever been able to crack a software using it. However, the users really hate the system and to have to buy an iLok2 key, and all the developers who have been using this scheme to protect their software with it really hate PACE support and all the crap necessary to compile anything with the iLok2 protection system, even when you just have to create an AAX plug-in.
You should look for Urs Heckmann's talks on the subject on KVR, it's really interesting, and he gave a few tricks he uses with u-he software, which seems to be the one with the best ratio for protection vs load on users. In short, he uses serial based protection, and some time bombs, his philosophy being of developing a not intrusive protection scheme, and ways to transform cracked version users into customers ;)
I will be at the meetup in Paris too, I spent a lot of time at Ircam during my student years ;)