For example: If a “Buy 1 Get 1 For Free” discount has an allocation limit of 2, then the discount will only be applied to the cart twice, even if there are more than 4 items.
If no allocation_limit is specified, the discount will default to unlimited uses in a single cart. If your app doesn't use this new parameter, then all discounts will have unlimited uses.
Apps that have created a Buy X Get Y discount type have been notified via email to their Partner account. If your app is creating these discounts and you have not received the email, then reach out to firstname.lastname@example.org.
Starting today, you can request this parameter be enabled for your application by emailing email@example.com. On September 10, 2018, the parameter will be active for all applications.