You’re a member of A.A. if you say you are. We don’t demand any contribution, neither in time or money.
However if you want to enjoy all the benefits of membership, in an international fellowship, most people find that sitting on the edges looking at the activity is not enough, they want to be involved. In A.A., this involvement is called doing service.
Service can take on several different forms
It might be making coffee, or cleaning up at your home-group meeting, essential tasks without which, the meeting wouldn’t work. One of the reasons that Continental European Region exists, is to enable English speaking members to do service in countries, where the language barrier might make it difficult for them to do so, or in some cases where there is no local fellowship.