Sb,
What’s crossover? It sounds like an program that converts a pc based program to Mac based program, is that correct?
Davka, IIRC, allows two installations, one on a pc and one on a laptop, as long as they’re not used simultaneously. Assuming they don’t make a Mac version, I can’t see why it’s a problem, and it might be ok even if they do. You should contact them; I understand the owner is an ehrliche Yid and reasonable.