You may update or change your billing information anytime by logging in to, selecting the user menu by clicking the icon on the top right, and going to "Account & Settings" > "Payment Options"

Our system automatically charges you on the same day of the month which you subscribed.  It will automatically attempt to charge you up three times within a 72 hour window.  If the final charge attempt is rejected, your account will be deactivate.  However you can reactivate it at any time by simply logging in, selecting a tier, and entering your new billing information.