Coupons are a little complicated for the reason that they are valid for a limited time period and after a certain validity period, they have no use. On Earningkart we mention everything about coupons so you can easily able to apply them.
There are also a few coupons knows as account-specific coupon, user-specific coupon, new users coupon, existing users coupon. These coupons valid for few peoples, we always mention these kind details before posting coupons.