Each National 折扣碼 has a different expiration time, you can select National 優惠碼 you want to use to redeem the discounts when making the payment. There are also some National 優惠折扣碼 that have a limited range of use, so you should also use it within the range. Such as a certain type of products, when the type of product has been sold out, then your National 折扣碼 is invalid.