The most common "keygens" are actually Trojan horses. Security researchers consistently find that over 95% of cracks from unverified sources contain malware. This includes:
Cybercriminals use the promise of a "free keygen link" to trick users into downloading trojans, ransomware, or spyware. stm swarna type manager 35 keygen link
If you have an old license key but cannot reinstall, run Windows 7 or 10 in a virtual machine (VirtualBox is free) and install from your original media. The most common "keygens" are actually Trojan horses