Pokemon Go has quietly added a new feature to the game: the ability to use promotional codes. Players with Android phones who enter the shop will notice a box to enter promotional codes, although no codes have been revealed yet.
According to Pokemon Go's support page, players can enter promotional codes to redeem items like Poke Balls, Lure Modules, and Lucky Eggs. We don't know how the codes will be distributed, but the page mentions that they'll be part of future events and promotions with corporate sponsors like Sprint, McDonald's, or Starbucks.
Right now the promotional codes only work on Android phones, as there's apparently still some legal issues to work out with Apple. Since Apple takes a cut of every in-game transaction, some fans think that Niantic could run into trouble if they charge sponsors for running some sort of in-game promotional code.
Players haven't figured out if Pokemon Go will use generic codes that anyone can redeem, or if they'll be some sort of code unique for each player. However, if the ability to redeem codes are live, we'd expect some sort of giveaway or promotion in the very near future.