If your payment is unsuccessful, your account will be put into a past_due status. While in past_due status, your account remains fully operational, giving you some time to update your payment method.
After several more unsuccessful attempts at charging your default payment method, your account will be put into an unpaid status. When your account is marked as unpaid, all your Device Licenses are removed which prevents you from accessing any Event’s Guestbook. You still will have access to you Events. If your payment method is updated and the past due charges are completed, your account will be made active again, allowing you to re-add your required Device Licenses.