It is completely free for non-professional use at home (without a controller).
Virtual DJ Pro is designed to be rock-solid during live performances. Preactivated versions are often unstable because the "crack" breaks the software's internal code. There is nothing worse than the software freezing or crashing in the middle of a live set at a party or gig.
One of the main reasons to go "Pro" is to use a DJ controller (Pioneer, Numark, Denon). Cracked versions often fail to recognize the latest drivers, leading to high latency, distorted audio, or non-functional jog wheels. Better (and Legal) Alternatives
If you buy a supported DJ controller, many come with a "Virtual DJ LE" (Limited Edition) or a license for Serato or Rekordbox, giving you a legal path to professional mixing. Conclusion