It is automatic.

The 30 days of billing auto renews every 30 days. The day you start, open, or fund the account is day one. You will be automatically billed 30 days from your start/open/fund date.

It doesn't matter what state the account is in until you cancel or pass.

It does not reset the balance unless the account is in a failed status at the renewal date.

If the account is failed, it is reset automatically for free.