I’m using since corporate Eset on Linux. When did they drop support?

Well, coming from a new Lemmy user, I just mean the platform, not the software or instance. We’re all federated anyway, right? Maybe I just don’t understand the difference that kbin offers over other Lemmy instances. Is it more? Then again, I’m also not entirely clear on why I need both a Lemmy account and a mastodon account.