I would like to propose what I think is a good idea for recoding the way NowTV detects whether you are using a new device or not.
Lots of people are now starting to come across the issue of exceeding your device limit or detecting your PC as a new device because;
a. You have upgraded from a qualifying OS to Windows 10 (but it is still the same computer)
b. Your Windows 10 has performed a major operating system update (but it is still the same computer)
Why cant the coding guys at NowTV change the software so it detects the network card MAC address? a MAC address is hardcoded onto the network device (either ethernet or wireless adapter) and this does not change when an update or upgrade is performed. I know this means that a PC switching between wired and wireless would be seen as 2 systems but lets face it, most people tend to stick with wired or wireless and dont switch about on the same device. MAC addess detection is the way to go everyone.
I have 3 Windows 10 systems at home, all registered on NowTV and now none of them work because of the latest Windows 10 OS update
That is a brilliant suggestion for the team. In the meantime, to assist with the device issue you are experiencing, I would recommend contacting NOW TV support. A one-time device reset can be accommodated due to the circumstances. Bear in mind, this will remove all registered devices from the account, allowing you to add the up-to-date computers/devices.