change user group action: some questions

I want to hide ads (displaied in modules) across the site for users who purchase a certain subscription

so i thought about using the "change user group" action

please help me understand if I created everything correctly:

I created 2 new user groups using as parent the "registered" user group

I have created the action to move in one of these 2 new groups the user when he purchase the subscription and to move out from the goup the user when the subscription expires

this last thing means thea the user will go back in the "registered" group right?

should I create the 2 new user groups using as parent a different group or no group at all, or it's ok like I0ve done now? (sorry, I know this last question is strictly not emerald related)

thank you