It's absolutely and definitely still being sold on this page: https://www.eset.com/us/home/antivirus/ and you can buy a license for it which I did this morning. I downloaded it and installed it without issue until I ran into the same issue others in this topic have.
Nowhere at any time in the entire process did I see any indication of any kind that this a legacy product or that it only receives limited support.
So I'm afraid either you or the part of the site that takes our money, is not telling the truth for whatever reason - I'm assuming a misunderstanding.
If I could receive a username and password ASAP that would be much appreciated, thank you in advance.