Hi @Anonymous User
Firstly i would check that your log in details on the nowtv App on your LG smart TV matches the details on your account when you went to My Account >Manage Devices.
If the sign in details on the LG TV nowtv App is correct and if you have a spare device slot or one additional device swap this month and for some reason it doesn't work, then i would try live chat and explain to them what's happening and ask them to reset all your 4 device slots allocation.
Then once live chat has done this, start watching nowtv content on the 4 devices that you want to use on your account.
Here's a link to live chat below.
https://help.nowtv.com/contact-us/managing-my-devices
