

Apple is now allowing Mac developers to create promo codes for apps in the Mac App Store. Per MacStories:
Promo codes allows developers to give out free copies of their App Store apps for review and giveaway purposes. This feature has long been offered to iOS App Store developers.You can now generate promo codes for your Mac apps in iTunes Connect. These promo codes can be redeemed in any Mac App Store worldwide. For each version of your app, you can request up to 50 promo codes.
Article Link: Apple Allows Developers to Generate Promo Codes for Mac App Store