You didn't had Steam version before, you had Android version? Or you first had Android, then you bought Steam, and then you again bought Steam?
As David said, you don't need to purchase game on any platform twice, once is enough (don't know if it will be possible with same account, I guess you can do that if you somehow have two or more accounts, but it is like you're two or more people, don't know how it works on one device). You only need to purchase game for each platform (PC, Android, iOS) again if you want to play it on that platform.
After that, you install game on wanted device(s) and you need to manually copy save files (EK.bak). Cloud save doesn't work with Steam, you need to do this manually, you can't do that through Steam, Steam cloud or anything Steam related.
Anyway, I just tried and started right now my Steam version, it is 1.2.1115. And it worked just fine.