Hello,
In case you have problems updating AntiVir PersonalEdition Classic and it says
Critical error: Keyfile: Key expired [DEMO Mode]
you can download a new keyfile from here:
http://dl1.avgate.net/down/windows/hbedv.key
and copy it to the installation folder of AntiVir (usually it's C:\Program Files\AntiVir PersonalEdition Classic). You may need to overwrite the existing hbedv.key file. Then restart your computer.
From this moment you should be able to update AntiVir. The key is valid for 3 months, but it will be automatically renewed through updates.
Best regards,
Radu