i successfully upgraded the av license, later did a pc restore. when trying to reinstall the license, getting message license is invalid
I would suggest contacting sales (at) avast (dot) com with the date when you upgraded, email address you used when purchasing the Pro license, you should obviously get that from the email that was sent with your registration key.
You could possibly send the registration key number, but you probably don’t need it if you do I would think they would ask.
Did you buy through the on-line upgrade using share*it or did you use an avast reseller ?
See the tutorial: http://www.avast.com/files/tutorials/insert_key.htm
Please take a look here: http://www.avast.com/eng/faq-invalid-license-number.html
Is your system date/time correct?
Do you use copy & paste method?
Are you sure you do not include the ‘last blank space’ in the paragraph while copying & pasting?
Which avast version are you trying to register (Home or Professional)?