It doesn't upgrade your account automatically. You have to click the link in the email you got. Many people are forgetting to do so.
It'd be good if the forum registration email mentioned that. I bought Drive a few days ago and only made my forum account today, and if I hadn't clicked this thread I'd have had no idea how to upgrade my account.
It says so in the e-mail. A picture pointing out the link, to be pasted in any/all threads asking this question. (imported from here)(pardon the awful MSPAINT work), and an attached version in case for whatever reason my Photobucket goes down and you can't link it from there anymore. Open the big one in a new tab to get the URL.
In the purchase email, yes. But not in the forum registration email. I get a ton of email, and as I said there was about a week between me buying the game and me registering for the forum so if you hadn't said anything I wouldn't have tracked down the purchase email. It would've been nice to have been told in the forum registration email to look for the link in the purchase email.
I understand that. Not everyone who has made a forum account has purchased the game, however. The information about upgrading to the premium account would not be relevant to those people. If it is the case that you actually did lose the purchase E-Mail, you could always file a support ticket as detailed in this thread. As you would have lost your order # I'm pretty sure you could sub in your serial key found in serial.txt in the install directory, As I'm pretty sure each order gets a unique serial that is logged in a database somewhere. Lastly though, any time I do business through E-Mail or receive a product through an E-Mail link, I always make sure to create a local text based backup of the concerned E-Mail. It's just good practice. P.S. CTRL+F is your friend.
I think some people have Beamng pirate and ask anyway for the Drive forum access.. (but maybe I'm wrong)