Thanks!
You’re absolutly right: If I choose “Force subscription”, it works!!
I wanted to be nice and choose “Yes, show option already checked”, which did not show up on the woocommerce registration, but did still prevent the subscription to take place.
=> I will probably go with “Force subscription”.
=> Still, do you see a way to implement the “Show option” … so that I could link your “checkbox” with a field I create in woocommerce registration form?
Thanks again, Gilbert