Tech was talking about the license key for avast Home (which you already have, or can get for free here).

setupengpro.exe is the installer of avast! Professional. I must say I’m not sure if you can use it to update an existing installation of avast! Home; maybe you’ll have to uninstall avast! Home first and then install the trial version of avast! Professional from scratch. When the trial is over and you want to go back to avast! Home, you can just enter the free Home license key into avast! Professional and it will “transform” itself into avast! Home.