The Fulfillment system adjusts inventory when items are fulfilled. If you are using a different fulfillment system that does not adjust inventory, you can configure the Commerce Reference Store order manager to adjust inventory on checkout.

By default, the Commerce order manager, /atg/commerce/order/OrderManager, is of class atg.commerce.order.SimpleOrderManager. Commerce Reference Store changes the class of this component to atg.projects.store.order.StoreOrderManager, which is a Commerce Reference Store-specific subclass of SimpleOrderManager. StoreOrderManager adds a Boolean property, adjustInventoryOnCheckout, which determines whether it should adjust inventory on checkout. By default, this property is set to false, because Fulfillment handles inventory adjustment. If you are using a fulfillment system that does not adjust inventory, set this value to true:

adjustInventoryOnCheckout=true