Now, that is what I ruled out as you had written:
Public Steam release was November 2013 … some of us bought the game in 2010. 
Yes, what the others said.
Hmm what’s weird is I have a memory of purchasing the game during kick starter period and not through Steam. That’s kind of where my confusion is, is it possible to have purchased the game through kickstarter promotion, then have it activated through Steam? If not, I think I may have been abducted by aliens and injected with false memory. God help me.
Yes, that is very possible. Everyone currently is on Steam, there is no other version, whether you bought it during KS, on Humble or Steam.
Well have you read Grim Dawn Alpha Release!? That provides information on how to get your key from the HumbleStore if you got via Kickstarter or the web site during that time period.
This sounds like you changed your email address after the Kickstarter. If this is the case and you remember it, then you should be able to login to the KS site.
That and what ibugsy wrote.
Now I wonder, if you also purchased GD via Steam …
Yes, the game has to be downloaded via Steam no matter how you bought it. But if you did buy during the Kickstarter you would have received an initial key to be used at Humble Bumble to get another key to then be able to download from Steam. So you must have a Humble Bumble account somewhere I think. Try logging in to the Humble store.
Thanks all, I’ll shift through old e-mails and such…
I’m totally buying Wisp for 5€ yay!
Which forum, specifically?
I would like to thank him too LOL 
Is there any way to upgrade your copy if you got it via Steam? I’d also want to buy one for someone as a gift, but I don’t think I can give away my current game version…
Sadly not. It may get added after release as a DLC upgrade, but no promises
There is a workaround - if you only want to gift the regular Digital Edition. Buy the desired version from this website respectively the Humble Store. Claim your Steam key and give it to your friend. On release you will get the “upgrade” key.
Hi, I have a question:
With the current sale going on ($12.49), what would be the cost of upgrading a standard copy to the Patron Edition? My wife is in the process of buying the Standard Edition, and was wondering.
I know it sounds stupid, but to me, it could either be a $15.00 difference (original price minus patron price), or it could be $27.50 (sale price minus Patron price).
Thanks, and cheers!
Uhm, so how do I do this now?
I bougt the game via steam during one of it’s sales (and I’m so glad I did) and now, I want to upgrade to the loyalist’s edition. I know I have to email someone but when I do, I get a new steam key? Or is the new steam key only for those who purchased the game via KS?
As everybody is currently playing the same Early Access version, you would not get a new key now - at least not one for a different edition. As for having bought from Steam:
Right.
I did read that.
So I just buy the $79 version, and then…what with my current copy?
Whelp, bought it, yay!
Here! Take my money!
Keep playing it. Later you can upgrade it with the Loyalist unlock-key.
It will be a bit of a mix-up, because in your Humble Store account you won’t see your current Steam key, but only the spare one, which you might give to a friend or relative.
Awesome news