Cancel and Renew Subscriptions
Once you have subscribed to a plan, users have the ability to cancel or renew anytime. To update your credit card or cancel your plan, you can use the Billing Portal accessed via the "Manage Billing" link at the bottom of your Invoices & Billing panel.
Subscriptions in Settings
Keep in mind that the subscriptions are monthly. When you cancel your subscription it continues to run until the end of the current month's period. For example, if you subscribe on January 1st, your payment will run from January 1st until February 1st. If you cancel on January 15th your subscription and minutes will continue to be available until Feb 1st. On Feb 1st, your minutes will be removed and you will not be billed for the month of February. This will be the case until you renew and start the process again.