Hi, thanks for the feedback!
My take is: user account is fine if that’s all what you take. Email and license should be enough data for you to be able to link all devices together. From a privacy concern perspective, email is public data anyway. GDPR disagree, I know, but come on…
As for android app not accessing network. I disagree on this statement and will argue that you are, since you’re able to tell me wifi and cell usage. Not “using” the network, sending data, OK, I trust you if you tell me you don’t.
But being a network monitoring tool, you have to touch the nics 
In fact, having a server somwhere would be even better. Your win app is one, so the android app could connect to it if we had accounts.
Anyway, we’ll see how the product evolves, you have to make it profitable too, I get it!
Alex.