You can find all your coupons in the 'My Offers & rewards' section tab. The expiry date will be mentioned on the coupon in red text. Once the coupon expires, it will move to the Inactive tab.
You can tap on the ‘Offer Details’ to know more about how you can use this coupon.
Your coupons will be pre-applied on contests and matches where it can be used. So keep an eye out!