Apple/Google handle all payments and subscriptions, not muzmatch. Monthly subscriptions are charged to your Google/iTunes payment method every month.
Biannual/Annual are charged once at the beginning of the term and renew at the end of the term unless cancelled.
Apple/Google control all payments - not muzmatch, and this is how they treat all biannual/annual subscriptions on ALL apps offered in their Stores.
muzmatch is treated no differently in this regard.