2

What is the full text of the error message (is there a more information, etc.) ?

Where did you purchase your license from, On-line at avast via, Share*it or a Reseller or another location ?
The reason I ask this is there are a number of fraudulent sites selling avast and other products.

Q: “Invalid license number”. Why? http://www.avast.com/eng/faq-invalid-license-number.html Or Insert Registration Key - Video