Hello jack157 and welcome to the forum.

What product of Avast do you have (Free, Pro, AIS)?

If you have a paid product, then contact Avast http://www.avast.com/contact-form.php?loadStyles and use the drop down menu for Sales Inquiries, then enter your information.

If you have the Free Avast, then you have 2 options: either wait until the expiration date (you get a 14-day advance notice from Avast to renew), or you can uninstall Avast and do a clean install and register with a new email address like you are starting fresh and register online. I would suggest uninstalling Avast via the Avast uninstaller tool http://www.avast.com/uninstall-utility, reboot, and doing a clean install. Please let me know if you need the download install files.

What version of Avast do you currently have on your machine? Was this an upgrade from 4.8 or a clean install?

The license key box has disappeared because you are now registered (it should tell you this on the main GUI page). You will get a 14-day reminder pop-up notice from Avast when it is time to renew again, but let’s try to fix this problem before then, otherwise, you can just do it at that time if you have the Free version.

I will await your reply to assist you further. Thank you.