It's not cheap to purchase outright, and I haven't as of yet, but it does have monthly and annual subscription models, as well as lifetime options. And you don't have to get all of the modules if you won't use them.
The Manuscript module could do with some tweaking to more closely compete with Scrivener, but I think it would compare well to Word or Google Docs.
But, the best thing is, it's actively being improved all the time and I'm super excited to see where it will go. They regularly upload useful and entertaining Youtube videos, as well, with great writing tips or just fun collaborative writing events.