If you can arrange things so that some (but not all) of the functionality in your app is unavailable in a pirated copy, then piracy becomes a form of trialware, and can be a huge marketing channel.<p>Way back in the day, I co-wrote an early networked multiplayer game on the Mac, <i>Spectre</i>. We didn't use copy protection, as it was too much hassle for legitimate users. However, there was a nontrivial-to-hack requirement that you have N serial numbers for an N-player game. This led to people pirating the game for the single-player mode, enjoying it, and buying a second or third copy for multiplayer. I don't have hard data, but we believe a lot of our sales originated this way.<p>There's probably some psychology at work here: if you let someone download a "trial version" for free, they may not value it as much as an app they had to "pirate".