Looks like React animation libraries are popular right now. Here's the one that I've been working on recently: https://github.com/ismailman/react-spho My philosophy is different though that I want to make it absolutely dead simple to make UIs animate organically vs being a feature-filled animation library. I think React-SPHO is actually the easiest to use animation library for React available as most things you want…
Why would anyone pay for your non-free software when there are hundreds of great alternatives?
One reason for paying is to ensure that the library is maintained: too many people out there assume that labor is free.
I would not pay for anything that isn't open source, though, because I do not want to become fully dependent on something that might disappear.