Only one copy of a product in a cart

Hi,

In the settings of your product, you have a setting "Quantity per order" with two inputs, one for the minimum, one for the maximum.
If you set 1 in the maximum input, your customers won't be able to add multiple copies of the product in the cart.

Now, they still can buy the product several times, by purchasing the product in different orders. If you want to prevent that, you can instead create a limit with a period set to "forever" and a maximum quantity set to 1 with the product selected in the product restriction setting of the limit:
www.hikashop.com/support/2-uncategorised...limits-tutorial.html