Can’t see your coupon in your account page? Probably that’s because you have not added anything to your basket yet. A coupon is valid and shown only when your basket is entitled to it. It is a little illogical to have a discount when you are not buying anything, isn’t it?
When a discount coupon calls for a minimum purchase of X amount, it will be shown only when that X minimum is reached.
When the conditions are met, a coupon is shown on the account page, the cart page and the checkout page, after you have clicked on the “Have a coupon? Click here to enter your code” link.