I really don't get it either. There must be a very easy way to set up your license no matter where you are and no matter on what platform. It could even extend your business model as a gaming company a LOT.
Imagine. Not punishing people who play 2nd hand copies, but offer new licenses with a discount. If a copy is recognized as a pirated version, just offer a new license (just like Microsoft does) again and again.
Stop punishing legitemate users, reward them! Add some nifty toy/jewel/piece of plastic crap/usb thing (at least something that can't be torrented, put under a Xerox or mass procuded by amateurs easily) with some unique id and/or unique data in it. Offer maps, clothing, bags, whatever. Don't use algorithms to make your unique serials, have them made by really completely random facts. (Like the weather, monkeys, etc). And give back to your fanbase! Less pirating? Cheaper games! Free maps, etc.