You can buy it once (I think it's like $5) to remove ads. I've been using the Reddit version since about when it came out. I've gotten a lot of use from it over the years, and I'm happy to have the same experience on Lemmy.
The guy deserves his $5 and the donations. Sure it's not for everyone, some people would rather not run proprietary apps, but sometimes it's worth paying for software. The key for me is, it's not forced on me: I chose that app. It competes on its own merits.
Maybe one day Jerboa will beat it, but in the meantime I appreciate the quick API backend swap and having a high quality Lemmy app in like about a month into the Reddit API apocalypse.