You may charge your member to join one of your membership tier.
If you are a physical store, you can simply collect payment as normal transaction at cashier counter and let the member register on the StoreApp with staff supervision.
If you would like to allow online registration and payment, you could setup in Settings> Payment
Enter you Paypal account email or Stripe account keys for transactional payment to your respective account
You could contact Eber Team for further clarification or guides