When you bought the HiB, you should've received an e-mail like this one:

Thanks scancode!

I've put instructions up on the twitter as well.

Shouldn't be too hard to figure out, but still.

Thank you Scancode :3

I Just bought the game, and my key does not work in the licensing,
Could the update email be resent to HB buyers? I think I bought the game after the update email.
Edit:
My link looks different:
https://humblebundle.appspot.com/s?key=XXXXXXXXX (edited out key)

I tried the other login with my email and key, but nothing happened when i clicked login - other than the text fields clearing.
What am I doing wrong here?

Nevermind I just had to change the link around..

Just added support for appspot keys. Yay!

Does it have to be a part of the humble bundle, not just a separate store purchase?

If you bought from the humble store, it works too

Could you add support for HiB3 keys?

The HiB3 bonus content came with the HiB2 stuff. I've got my HiB3 with Cortex Command and cant use my keys to update. :C

When i bought from the humble store i dident get a key it just gave me the direct link to a page with the cortex command download so i claimed it with my humble store profile

Copy that url and paste it in the space where the link below the pic takes you.

copy the url of the download page for cortex command?

EDIT: Never mind found out on my own i copyed the store page of cortex commands url and i got my latest copy

Can i enter my key a unlimited amount of times? I might get a new laptop soon

Yes.

It's just used as login credentials.