Producers will often run package deals on their beats, such as 3 beats for the price of 2. These are very easy to activate - you simply add the qualifying beats to your cart and the discount will be applied automatically.
Producers can choose which licenses are included in their discounts, and which beats are included. So when adding your beats to the cart, make sure they have the '%' icon, which indicates they are included. You will know the discount has been activated as it will be instantly reflected in your cart, as shown below.
You will also notice there is an 'Add Coupon' button in the left-hand panel. Coupons can be added here or during checkout. Coupons are set created by the producers, and are only valid in the store of the producer providing it. They cannot be used on the Airbit Marketplace.