Many sites offering free codes bundle the "activation tool" with trojans, miners, or ransomware.

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Instead of risking your data with questionable links, consider these legitimate alternatives:

If Avast detects an invalid or pirated key, it will stop providing virus definition updates, leaving your computer vulnerable to new threats. Safe Ways to Get Avast Premium Security

These are volume licenses intended for businesses that have been shared illegally. Avast frequently blacklists these keys once they detect abnormal usage.