Gemmeg hello, it seems that there is a misunderstanding. FreeFlarum is a free and community provided forum hosting service that uses the Flarum software under the hood, and is not affiliated with it. FreeFlarum allows you to export the full data of your forum at anytime in the settings, please see https://docs.freeflarum.com/en/tutorials/exporting-forum/ for more details.
It is therefore possible to start a community at FreeFlarum and migrate it to a different hosting provider later. It’s what the service is about - to allow people to start their communities, and later migrate to a more powerful hosting, should they grow enough.
