If you're looking for affordable options, you can consider:

Using license keys found on sites like Scribd, Quora, or YouTube (often shared as lists of serial numbers) carries significant risks: Free ESET License key | ESET NOD32 Antivirus

Leo clicked. A string of twenty characters appeared. He copied them into the Eset activation window, held his breath, and hit 'Enter.' The progress bar crawled.

A forum post from 2022 with a list of alphanumeric strings. The Third Link: A "shopping" tab offering keys for $0.00.

Rather than searching for unverified keys that may contain malware, consider these official options:

Occasionally tech sites (like GiveawayClub or major YouTubers) run — but verify the source carefully.