Enter in your Coupon Code when you sign up . See below for the exact spot. Coupon Codes are case & space sensitive so be sure to use all caps & no spaces if the Coupon Code comes that way.
When using a Coupon Code you must enter in a credit card, however, your card will not be charged until the Coupon Code expires.
If you do nothing then your card on file will be used to start the membership subscription that you selected.
Cancel your subscription before the Coupon Code expires and your card will not be charged. However your membership can be reactivated at any time in the future by logging in and selecting the “update payment info” button at top then the “update” button next to your subscription.