First, you need to buy a license key from an authorized AVG reseller or directly from the official AVG website.
If you already downloaded any “activator” or “patch” from a site offering this key, run a full scan with a trusted antivirus (Malwarebytes Free, Microsoft Defender, or a fresh AVG installation from the official site).
If you need protection without the risk of a compromised license:
Legitimate codes are sent via order confirmation emails from notification@mails.avg.com or found inside official retail packaging.