About game purchases

Hello! So, I have purchased few games (Hosted Games) from steam and then learned there is an iOS app for Hosted Games, purchased them again there. Recently though I’ve learned that there is an option to email Choice of Games receipts of the purchases and they can unlock it on other devices (iOS or Android). So, question is, how common is that? Is that a usual thing and they unlock stuff regularly or is it more of an exception to the rules? Thanks!

See this thread: