Even if keygens worked perfectly (which they don't), the risks would far outweigh any potential benefit. Consider the following threats.
: Avast Antivirus itself is designed to detect and block "Tools" like key generators during its Boot-Time Scans to protect your system. Safe Ways to Use Avast for Free avast key generator work
The keygen attempts to reverse-engineer the logic Avast uses to validate serial numbers. Even if keygens worked perfectly (which they don't),
If you're caught using a key generator or a fake license key, you may face: avast key generator work
The short answer is: No, Avast key generators do not work in the way they claim, and they are almost universally used as vehicles for malware.