A better alternative would be to separate the core open source app from any premium, proprietary add-on features, as the developer hinted at here.
As someone else pointed out, it’s difficult to agree that this app follows an open source model when the open source portion of it is essentially non-functional and requires the closed source components to be of any practical use. Until that separation occurs, this isn’t really open source; you’re trusting a stranger on the internet with your (or your client’s) network credentials.
Barring any similar apps, I’ll stick to my password manager and terminal.