I've gotten my NFC Express today and I've tested the login function with the supplied Asus NFC Tag, reading the NFC Tag it seems to store the username and then it seems to store the password but not in cleartext, it's probably a hash or the encrypted password. It also works nicely with Android Smart Lock at the same time without having to rewrite anything, so I can use the same key to unlock my phone and computer (will be handy for when the ring (hopefully) arrives)
My system is running Windows 10 pro, so I was uncertain whether it would work or not, but it appears that it's working just fine, at least for me. I did have to install the Windows 8.1 drivers but they're seemingly working fine. Although worth noting is that I've only tried the login function so far. So while it may not have official support for Windows 10, it does seem like it works with it.
Now the only thing missing is a ring. ^-^