Never download security software from third-party "warez" sites. It is far safer to use a legitimate free antivirus than a compromised "Pro" version.
Most "cracks" or "keygens" are actually Trojans or Ransomware in disguise. By running the installer, you are giving an unknown program administrative access to your system [1, 2].
Cracks often require you to disable your existing antivirus to install them. This leaves your computer completely defenseless during the process [1].