How can I make it so people can only use a coupon once?

You may want to give out coupon codes but not want customers to abuse them. BigCommerce allows you to limit the number of uses per customer.

Go to Marketing > Promotions and click the Coupon tab at the top. Edit the coupon and then scroll down to the Usage Limits section. Check the box for “Limit number of uses per customer” and then enter the number of uses you want. Don’t forget to save when finished.

Please note that the usage restrictions apply based on customer account (email address). It’s theoretically possible for a customer to create multiple accounts and then use the coupon more than once.