How to limit a service or product to one per order

Hello!

For one of my service that I offer on my website, I would like my customers to be limited to only 1 quantity  per order.  Basically, I don't want them to be able to press "add service" twice to the cart. How can I do that?

Furthermore, once the customer is on the checkout page, the quantity field is editable. How can I make it uneditable so that the quantity is fixed to 1 ?

Thanks ahead for your time in answering this. 

Best,

Charles

There isn't a way to enforce this but you can encourage it.

I say this because you cannot do anything about the checkout stage. This will always be possible, until Squarespace remove this feature. You can add your voice to the requests to do this by raising a ticket through Customer Care. They'll document your feedback and share it with the appropriate team.

One way to encourage it is to hide the quantity option so that users don't have the opportunity to change it to more than one. You can then enable Express Checkout. With this enabled, a customer is sent straight to the checkout, bypassing the cart and further shopping.