There's an entire paragraph on that page about it
>This isn’t a scaled-back version of Phabricator. We only build one version, and that version is free, open, and built to scale. There are no special keys or licenses needed. No community or enterprise versions. Code quality and engineering efficiency is too important to us to split up features. When you’re ready to move off of the free tier and bring your whole company, you’re welcome to upgrade on Phacility, or take your data with you and host it locally. We’re glad to have you as a customer either way.
