Promo codes on Google and Apple

Promo codes allow you to give a limited number of end-users access to paid apps or free apps with in-app purchases free of charge.

• You can offer promo codes for both paid apps and free apps with in-app purchases on both Google and Apple.
• Promo codes are unique codes and can be redeemed once.
• Both Google and Apple platforms set limits to the codes. For example,
  • Google: you will need to set a validation range for the codes. You can create up to 500 promo codes per quarter across all managed products in an app. 
  • Apple:  you could not set an expired day for the codes on Apple. Instead, the codes will expire after four weeks from the day they’re generated. You can provide up to 100 promo codes for each in-app purchase product, with a limit of 1,000 total codes for all in-app purchases for an app every six months (resetting on January 1 and July 1). 

Official guide from Google and Apple:

Create promotions on Google

Promo codes on Google

Request and manage promo codes on Apple