User blog:ImAcuteLittleBee/Please help me.. (Some buying robux using Google Play discount issue)

I saw today that Google Play gave me 80Rs discount. (Approx. 1 dollar). But when I'm trying to checkout it goes to buy. I'm scared it will cut my real money. I'm purchasing 80 robux. And the cost (including tax) is coming Rs 79.. But where can i redeem the discount. I know that payment issues are kind of personal but please help me, if this is successful it will be my first robux.