After you do this, your app will download to your phone or tablet. If you’d instead redeem the code on the desktop. Click the Redeem tab on the left of the Play Store home screen. Then type or paste your code. As you can see, the process is simple. You’ll probably spend way more time chasing down promo codes. Keep an eye out on Twitter, as they’re the popular outlet for companies and developers to throw out such freebies.