Rust Serial lost?

I bought Rust a long time ago when you could first buy it to get inside the alpha. now since it does not use the browser anymore i cant play it.
I have the receipt from my original order, how do i get a new serial to use in steam?

Sign in here. Click on Steam Key. Activate on Steam.

If you can’t sign in and resetting your password doesn’t work, you’ll need to contact FP Studios for help.

Thank you, got me key now :smiley:

enjoy the game :3