Google Play may offer complimentary redemption codes when sponsoring an event, but free codes can mainly be sought from surveys, which can be done online. Other than surveys, however, the codes must be purchased through online or department stores.
Survey websites, such as Swag Bucks, allow opportunities for users to complete surveys on products. Once a user completes enough surveys or tasks, they are then eligible to receive points. These points can be turned into Google Play redemption codes.
Other cards can be purchased through online retailers and standard departments stores, such as Wal-Mart and Target. These codes can then be redeemed online for digital products.