Congratulations! Having cracked versions out there indicates that your software is both useful and notable, which is a point where many developers would love to arrive at, maybe, one day. As to what to do about it, there are two basic tracks, neither of which is incompatible with the other: 1. The legal route: notifying distribution sites that they're hosting content in violation of copyright law, requesting takedown…
Indeed! There's a nice anecdote from Paulo Coehlo (I don't like his work but w/e) where he was stuck in traffic somewhere in LATAM and a guy passed by his car selling pirated copies of his newest book. He then says this event made him feel like he had finally made it and even became a strong promoter of piracy, heh.