When a customer enters a valid coupon for your product, or accesses your product from the coupon URL (which contains the coupon directly in the URL and applies it automatically), we persist this coupon for them.
This means that if they refresh the page, or click the back button and then return again, their coupon will still be applied and ready for them to go.
If you want to prevent this functionality, you can simply add a parameter to the query string when sending people to your cart.
Here follows some simple examples:
Default behaviour: this is a standard coupon URL, and the coupon will be applied automatically and then remembered if the customer clicks back and then returns later.
If the user clicks this link, then enters a valid coupon themselves, it will not get saved and they would have to re-enter it if they leave the page and come back again.
If the user clicks this link, the 'DISCOUNT' coupon will be applied automatically. If they then click to go back, it will not be saved and they would have to re-enter it again.