The Expire Coupon action allows to automatically disable a coupon when countdown timer runs out, and displays an expiration message each time a user try to apply the coupon code (see image below).
Create a coupon under WooCommerce → Coupons or Marketing → Coupons ( Note: Leave the Coupon expiry date field empty)
In your HurryTimer campaign settings, click the Expiry Actions tab, select the Expire Coupon from the actions dropdown and choose the coupon code.
3. Save the changes and that's it!
No, displaying the countdown timer on the font side of your website is optional.
Only one coupon is needed (which you specified when adding the action). The coupon will expire only for users with expired countdown timer and simultaneously will stay valid for users with running countdown timer.