That seemed very odd that for you to even buy on the shop you need to pay annual fees.
Did you get asked your password before? Not that you're confusing the password demand for your account or the Nintendo Network ID (NNID, which will pop up every single time you want to access to the eShop) with one for the Nintendo Online?
The Nintendo eShop rating Thread: http://gamrconnect.vgchartz.com/thread.php?id=237454
The Steam/GOG key gifting thread: https://gamrconnect.vgchartz.com/thread/242024/the-steamgog-key-gifting-thread/1/