the win on this article is the comments: he posted the article, someone cracked the license generator, posted the source. there was a brief, friendly discussion about this.
if it were one of my previous employers, they would've immediately sic'd lawyers, the fbi, homeland security, and anyone within shouting distance on the commenter. (the head of the legal department once got up at a quarterly meeting and ecstatically announced how many people had been prosecuted that quarter. there was an uncomfortable silence that followed, as everyone began expecting security cameras installed in every room. they started appearing shortly thereafter.)
the authors sense of humor about this and pragmatic outlook is appreciated, and in my mind, correct. do what you can, make it easy to buy, make it uninteresting to break, have free versions available for people who need them.