I’m using the Digital Products plugin to sell licenses so that users are listed on the site for a certain amount of time.
The options are something like "buy 3 month", "buy 6 month" etc. You see, the concept of the cart doesn’t really apply here. There would be no point in buying "3 month" twice.
That’s why I’d like to set the items in the cart always to the quantity of 1. Even better would be if I could empty the cart each time a product is added to the cart. That’s because people are supposed to select between the given options, not buying several options at once or multiple times.