I don’t know exactly how Site.Pro manages their storage.
Site.Pro is the website builder we provide (as evidenced by the Site.Pro logo in the top right corner of the builder).
Site.Pro is indeed it’s own entity. It has it’s own features and limits which are independent of your hosting account.
But you’re by no means required to use Site.Pro. Our hosting is a blank canvas and you can host any PHP/MySQL-based website with us. This article covers a few different methods you could use to build your website:
If you don’t want to use Site.Pro, you can switch to something else instead. However, do realize that you may need to recreate your entire website in a new system to do that.