Why my Avast License Key is too long?

If you're trying to activate avast! antivirus products but end up with an error message saying that your product key is too long or there's not enough space in the form to enter the whole license key number, then you are probably using an outdated version of Avast.

This problem usually occurs in avast version 4.5.561 and previous versions.

To resolve the issue, simply download the latest version of avast antivirus, and re-install the software.