I paid by credit card for a renewal of my antii-virus protecation, professional grade, and I have since gotten a notice at least every day that it was about to expire. It would not accept my license key, the one you sent me via email. I either need to have my key accepted or will have to contact the credit card company to dispute the charge since you have not delivered the product I have paid for. ???
Hi mitch48, welcome to the forum 
What is the error message you get?
Can you double check the system time and date?
Do these help?
avast! license key tutorial
avast! FAQ >> Invalid License Number
Also, where did you purchase the license from?
-Scott-
Also, make sure there are no spaces before nor after the license key.
How do i enter my license key # for my avast needs help . 
:-\
How do i enter my license key # for my avast needs help .Scott already posted the tutorial.....
That tutorial you posted shows the old interface, with the blue icon. there are no instructions on how to enter the license key for a Pro version. It wants a license “file” but I received only a text code in an email. Where can I find this file and download so I may activate this software.
Write your email address and your key here:
http://www.avast.com/resend-license.php
And the license file will be sended to you.
Because at the time that it was posted avast5 hadn’t been released (19/1/2010) so the post was in response to a 4.8 problem not 5.0.