If you signup for our Free plan, we don't require a payment method, and you will never be billed unless you decide to upgrade to one of our paid plans.
On paid plans, you are billed when you subscribe to the plan, and will be re-billed after 1 year unless you cancel before the plan is renewed. Paid plans are renewed 1 year from when they were originally ordered, within approximately the 24 hours proceeding the day of renewal. For example, if you ordered a paid plan on May 3, 2015, your plan would be renewed and re-billed within a 24 hour window of May 3, 2016.
If you wish to cancel your paid plan, you may do so at anytime before the plan is renewed by switching to the Free plan. Your existing paid plan will continue until it expires, and then you will be switched to the Free plan without being re-billed.