There is no additional charge for using this functionality.
Non-Consumables contents are In-App Purchases that only need to be purchased once and are available to all devices registered to a user. This purchase type is used for services that does not expire. Non-Consumable In-App Purchases are available for both iOS apps and Mac apps. After the user makes a purchase, you can use the SKDownload class in Store Kit to download the content to the user’s device.