If you downgrade to the Free plan, you continue to sell your books and courses on Leanpub.
This is why we have the same number of books and courses in the Free,
Standard and Pro plans: we want to continue selling your books and
Currently, after you downgrade to the Free plan, you will still be able to preview and publish your books and courses in their current writing mode, but subject to the Free plan's limitations on the number of previews and publishes you can do in a month.
This will not affect the way your books and courses are presented on Leanpub. They will be available for sale in the bookstore etc. just like when you were on a paid plan.