In case you enter a discount code during checkout that doesn't exist or isn't currently active, then you can see the message: “Unable to find a valid discount matching the code entered”.

Simply, access the Grammarly.com site and find your coupons bar. All the latest

coupons will be shown out, note that the coupons bar will only appear when you have coupons available.

Normally, one discount code is only applied for one offer. However, If the users put a vast of items in their cart, it is easy to use one coupon code to purchase items. It depends on Grammarly.com's policy, you can contact Grammarly.com via mail for your reference.

Yes. The old coupons from Grammarly.com will be kept on the page if it has not expired. New coupons will continuously be updated.