I have no first hand knowledge, but it is my understanding based on what others have told me that IDA Pro is actually kind of difficult to crack and pirate.
I don't know how true this is, but it makes logical sense - the developers of a reverse-engineering tool are likely far more clever at anti-piracy mitigations than your average programmer.
with a certain regularity ida pro versions leak, because companies who purchased ida pro get hacked. sometimes these ida pro versions are only available to a select few (the hacking crew, their friends etc.) but sometimes even those versions get leaked.
