The title you are commenting on is the genuine game for PC + Android. The title Darkest Nightmare has linked to is the fake and we are going through the process of getting it taken down.
Unsure if you ever got the answer. But all purchases are tied to your account, and typically buying into a game is like buying the tier of which version. Meaning you should have access to pc, mobile, mac, w/e if you bought it as they are on the same technical tier. You bought the game, you have all versions for that tier. (I use a tier list example because some devs charge more for most recent updates and less for older updates, while updates even older are free. Thus a "tier list")