If you have a Redemption/Voucher code, you will be able to use it inside the game. Just follow the instructions below to be able to use your code.
Code Redemption Proper
1. Open/Launch Slots Reel Frontier.
2. Tap the upper left corner of the screen to open the Menu options. You will see the Menu Icon on that part of the screen.
3. After opening the Menu, go to Inbox to continue.
4. Upon opening the inbox, you will see a Redeem Voucher button below. Tap it to open the redemption page.
5. After, you will be able to see the redemption page. See image below for reference.
6. Just enter/input your redemption code in the dedicated area then tap the Redeem button. You will see a confirmation message if you have successfully used the code.
"Enjoy your rewards and keep those reels hot and spinning! - gumi Team"