Hello! I correctly understand that to export a project from a free account you need to pay $ 15? Or when changing the tariff plan projects are lost?
To export a build of a project, you do need to upgrade your account from Free to Personal which costs $15 a month.
You do not lose any projects from upgrading from Free to Personal.
If you cancel the Personal plan, I think you only get read only access to your private projects. @will should be able to confirm/correct.