Gift cards and discount codes can be entered during checkout (tap ‘Show order summary’ on mobile). Only one discount code can be used per order. Discount codes expire after the promotion has ended (usually 1-2 weeks), and cannot be used more than once. Discount codes do not work with discounted product bundles since there is already a discount being applied, but gift cards can still be used. If you have already used a coupon code in the past, you will likely not be able to use it again for a second purchase.