Hey @maurizio.polverini89, your app will remain available on the stores. Once it in the stores, Thunkable has nothing to do with that app anymore. They simply act as the build and delivery service.
That said,
be mindful
you will not be able to edit a private project if you go from pro to basic. also, if you have any webapps published, they will become unavailable. Apps on the store won’t be affected.