You are the rightful owner of your content.
Depending on the theme that is used to create your site, you may be able to take the theme with you. Often paid themes do not come with resale rights. As such, you would have to recreate your site if you move it away from our hosting solution. However, do keep in mind that many providers will be in the same boat. They purchase the theme for use on their platform, and you have to recreate the site if you want to host it elsewhere.