Any account that has a rented phone number, whether it's active or disabled, incurs a monthly fee. This rule applies even if the number isn't being used. If the number isn't being used, you won't pay usage fees. If you close your account, all the numbers associated with that account will be released and the account will be deleted. You can close your account from the profile settings page of the Plivo console.
Accounts that are inactive due to pending verification, or suspended due to detection of fraudulent activity, incur phone number rental fees.