You have 60 days unrestricted access using the demo key, so there is no rush but I would have expected you to have received it by now.
I would try the other email address, ensure if you or your ISP have any anti-spam filters that avast.com domain is accepted.
What was the domain name of the email you gave first that you haven't received the registration key, e.g. xx @ your-isp.com or xx @ your-free-email.com ?