Informacja ta znajduje się w FAQ KSP. Jeśli kupiłeś grę przez stronę KSP, nie czytając FAQ, to było to troszkę niebezpieczne.
I bought the game on the KSP Store, but I want it on Steam. Will you give me a Steam Key?
Yes, we now offer the choice to transfer KSP purchases from before the game was available on Steam, note that this process is OPTIONAL and IRREVERSIBLE. If you transfer your purchase to Steam, you will no longer be able to download or update the game from the KSPStore, but also nobody's forcing you to go to Steam, if you opt not to transfer, you can still download and update the game as usual. To move to Steam, log in to your KSPStore profile and you will find the button to start the process next to your download link. Again please note that you will only be eligible for a transfer if you purchased the game before it was on Steam, no exceptions, please don't insist.
Z tego, co zrozumiałem, jeśli kupiłeś grę, zanim stała się dostępna na Steamie, to na stronie KSP obok przycisku pobierania powinien znajdować się przycisk transferu.