If your account has a history of past-due payments and/or other payment issues, subscription terms for you and your customers will be limited to monthly, regardless of what a vendor makes available, unless the subscription term is paid in full upfront.
If your account has customers currently enrolled in annual subscriptions and continues to have late payments, you may be required to have your account set to autopay with a confirmed credit card, or you may be required to pay the balance of all annual subscriptions in full prior rather than continuing on with month-to-month payments.