Even this blog warned me about posting to this 2+ year old question. But I have the same question and would like to have an answer from someone who is qualified to help me. I have installed Avast Pro on my MacBook Pro. I am also running Windows 10 under Parallels on this computer. Do I need to treat the Windows side as a separate device and install Avast there, or is the installation on the Mac side all that I need to do? Thank you.