While the 2038 license key was a legendary "hack" in the early 2020s, it is no longer a reliable or safe way to protect your PC. Stick to the official free version or consider a legitimate paid subscription if you need advanced features like a VPN or enhanced firewall.
The year 2038 isn't arbitrary; it relates to the (similar to Y2K) in computing, which is the maximum date many 32-bit systems can handle. In the past, certain "pro" or "premier" license files were leaked online that, when applied to Avast, showed an expiration date of 2038.
Many sites offering "license loaders" are actually delivering Trojans or ransomware.