The version number 3.2.36 is quite old, and many sites offering keys for this specific build are often "honey pots." When you download a torrent or a "key generator" (keygen) for antivirus software, you are likely downloading bundled malware.

While Malwarebytes tries to keep old versions updated, the modern "Katana" engine in the latest releases is specifically designed to stop zero-day exploits that version 3.x might miss.

Searching for a is a high-risk, low-reward move. You’re likely to end up with a virus instead of a virus-remover.