I'm coming here after confirming with customer support that this is indeed 'working as intended': WiFi Privacy keeps asking me for login credentials every time I kill the app (after working in an environment where I don't need a VPN) or after using my PC without a network connection. This makes absolutely no sense from the UX perspective, especially when there's no way to change that setting.
In the end, WiFi Privacy is a secondary security measure, ideal for people who travel a lot and thus need to use all kinds of hotspots: hotels, airports, lounges etc. It really is a major pain in the ass for a transparent VPN, not any sort of secure company network, to require a login and password multiple times a day. Other Norton products on the same PC are happy to remain logged in to my Norton Account and remember who I am, WiFi Privacy needs to get its act together.
tl;dr: Please let me remember my login credentials for WiFi Privacy permanently (with necessary warnings attached if need be). WiFi Privacy is not the primary layer of security on my PC, there's no need for it to keep asking for authentication.