Coupon/discount codes

Site URL: https://www.wrklfe.com/

For online discount codes to have real value, the functionality of having the code be a one-time use must be available. I understand that that is possible, but only if I pay an addition $25 a month?!? Other platforms offer this functionality for free. Without setting the functionality to one-time use, there really isn't much different than just putting an item on sale. 

I am a small business, and I would like to reward my customers with a coupon occasionally for free products to help build brand loyalty, but this is not an option because I have to pinch every penny as I try to grow my business, so another $25 a month is really not an option for me. 

I don't understand why Squarespace can't put limit amounts to the usage and only charge if a certain threshold is crossed. Putting this functionality behind a high-cost wall seems like it is just greed in a time when large companies are making record profits and small businesses struggle.