I've had the same issue, the difference is, I verified that my credit card was charged for the game purchase on 8/27. I've played during both the last beta and Early Access.

I've put it tickets with both SE and Digital River, and both replied with the same "Here's how you download the game" auto response.

I've checked every mailbox I have, and haven't gotten anything on a new registration code, and while checking noticed I never received a confirmation email from Digital River on the purchase of them game (yet I still have the charge on my card).

I'm still waiting on another response from Digital River, but here's hoping.