When it comes to the selection of only apply discount once per order, I want to say offer a discount for 4 of an item sold. If I don't select once per order will it then discount the 5th,6th,7th etc. Or keep discounting every 4 like I want?
Selecting the checkbox to set a maximum number of uses per order will limit the amount of times the discount applies on an order.
If you want the discount to continue applying when a customer adds more products to their cart, leave this box unchecked. For example, if the discount is buy 3 get 1 free, leaving this box unchecked will allow a customer to buy 6 and get 2 free, or buy 9 and get 3 free, etc.
Further down the page in the discount settings, there is a section for Maximum discount uses, where you can limit the discount to one use per customer if you'd like. This option would prevent the same customer (same email address) from placing multiple orders with the same code.
Sophia | Social Care @ Shopify - Was my reply helpful? Click Like to let me know! - Was your question answered? Mark it as an Accepted Solution - To learn more visit the Shopify Help Center or the Shopify Blog