Many search results and "crack" sites promote license keys that supposedly last until 2040 or even 2054. However, these are almost never legitimate for several reasons:

Sites offering "links" to these 2040 keys often bundle them with "keygens" or "cracks" which are frequent carriers of Trojans, ransomware, and adware . How to Get AVG TuneUp Legally

AVG Support confirms they offer annual or multi-year subscriptions. They do not currently offer a "lifetime" license to the general public.