Thanks for reaching out to Jotform Support. Thanks for reaching out to Jotform Support. Unfortunately, it is not possible to add promo/coupon codes when you use the Jotform Store Builder. As a workaround, you can create a form and use the Product List Element where you can add coupon codes. Here’s how to do it:
Open your form in Form Builder and select the Product List field.
Click on Product List on the right side of the field.
Under the Coupons tab, click on Create Coupon.
Enter a Coupon Code and choose a Coupon Limit.
Select a Discount Type and Rate.
In the Apply Discount section, select All.
Now, just click on Save and that's it. You're done.
Now, your customers can use your coupons to get a discount when they buy your products, like in the screencast below:
After creating the form with the coupon codes, you can create a Jotform App with the form or embed the form on your current Jotform App.
Give it a try and let us know if you need any other help.