You can get your MightyCall account & subscription overview and manage your add-ons and additional features in your Account Summary section. Here's what you can do:
Switch your subscription to a different plan.
View your estimated charges.
View your next billing date.
View your payment method and change it.
Enable international calling.
View your currently available refill minutes and add more to your balance.
Add/remove extra number slots.
Add/remove extra user seats.
Add extra MMS.