Bottom line:
Workstation Player is free. for non-commercial (education/hobbyist/home) use. Workstation Pro isn't,, so you won't find a "product key for free activation of VMware Workstation Pro" on VMware's site. And you'd likely find the admins of this site shutting down anyone trying to post where to get them because, well, VMware is hosting these communities.
You do have a legal and free option - and that is to use Workstation Player.
Give the stealth nature of the warez markets, it doesn't surprise me that VMware doesn't take the time to go and shut them down.
What are the repercussions? It's considered piracy (a nice term for theft) to run a product that hasn't been licensed legally. Large companies would be sued if they did this. Individuals do so at their own risk.