Thank you Marc.
I read the post and your answer, but I'm sorry, I still don't understand, how to set up this subscription in the following way:
1 - When a guest buy immediately a subscription plan (without having yet an account), he will be added to a paid user group called "Paid Member Group" (with specific permissions)
2 - When its subscription ends, he is automatically downgraded to a "normal" non paid user, in a group called "Member" (with specific permissions)
How can I be sure that he will be downgraded in this specific user group called "Member" ?
By the way, I don't understand neither how works the "reset" function.
Many thanks for your help.
Livio.
PS: Is it possible to create manually a subscription with start and end date, for my members (imported from my other website) who paid by an other platform then "Commerce" (I mean who became member using an other ecommerce platform).