PROBLEM
I have just purchased Avira Antivirus Option, how can i enable it?
SOLUTION
First load your new license from menù System->Appliance->License Settings (System->License Settings in version 3.x) and reboot your Libra Esva Appliance as suggested.
Next go to menù System->Content Analysis->Anti-Spam settings->Antispam Action Settings (System->Spam & Quarantine Settings->Antispam Action in version 3.x) and at the bottom of the page enable the Avira Option.
Save Settings!