Congratulations on receiving a promotional code! This page explains how to redeem your promotional code.
Redeem from iPhone, iPod Touch, or iPad
(1) Launch the “App Store” app from the Home screen of your iPhone, iPod touch, or iPad.
(2) Tap “Featured” tab in the bottom-left of the screen. Then, scroll all the way down of the page.
(3) Tap the "Redeem" button.
(4) You may be asked to login your Apple ID (email and password).
(5) Tap "You can also enter your code manually."
(6) Type in your promotional code and then tap "Redeem" at the upper right hand corner.
(7) Wait until download is complete.
If the App has been already downloaded and you have the promotional code for activating the Premium plan, you can redeem your code in the same way.