Who turns it on
The member, from their portal. Not you.
That is deliberate and it is not a limitation. Storing somebody's card because you typed it in on their behalf is a conversation you do not want to have with your bank, your members, or a regulator. The member adds their own card, to their own Stripe customer record, and can remove it the same way.
What happens
When a dues invoice comes due, Sembr charges the card on file. The member gets a receipt. The invoice settles and their membership advances.
Nobody does anything. That is the whole feature.
Failed cards
Cards expire and banks decline things. When a charge fails, Sembr tells the member what happened and what will happen next, without implying they did anything wrong.
The invoice goes back to being an ordinary unpaid invoice, and the normal chasing applies from there.
Cards about to expire
Sembr warns the member before the card expires rather than after it fails. A reminder in advance costs one email; a failed renewal costs a phone call and sometimes a member.
A lapsed member with autopay still gets charged
If somebody fell behind and later put a card on file, or their card recovered, Sembr will charge them and the payment reinstates them.
Lapsed is a statement about what is owed, not a block on paying it. Refusing to take money from a member who is trying to pay you would be an odd way to run a membership organization.
It cannot double-charge
Two things happening at once on the same invoice, a member paying manually in the portal at the same moment the nightly autopay run reaches them, is exactly the sort of race that produces a duplicate charge in a system that was not built for it.
Sembr takes a lock on the invoice before any charge, so only one of them can proceed. The other finds the invoice already settled and stops. This is not a retry policy or a best effort; the second charge cannot happen.
Turning it off
The member, from the portal, at any time. Their next invoice arrives normally and they pay it however they like.