You will have the option to enter a promo code when you register. If you have completed registration and never entered a promo code, you can still enter one. Tap the menu icon on the 'PAY NOW' screen, and tap “Promo Codes”.
After you’ve entered the promo code you will receive the promotional product as a Yoyo voucher. Swipe left from the main screen to the “REWARDS” screen to access it. You can only use one promo code per person!