I am not aware of any region restrictions, this is an HB key. You know the usual "let me give it to someone else if you happen to have an unexpected problem with this key" speech.

So... there are good news and bad news.

The bad news is that, for some reason, after a year, humblebundle decided that I had subscribed again to their service, and I didn't notice up until three months later when the email with "thank you for your purchase" kind of stuff popped up right when I had the phone in my hand.

The good news is that now I know where I was suspiciously losing money, and also that you get a few giveaways for the games that do not interest me!