If you've been watching NOW TV on an older model of YouView box: DTR-T1000, DTR-T1010 or DN370T, and you're now getting a message saying NOW TV is no longer supported, this is because your box cannot support the latest version of the app.
The NOW TV app will continue to work on all other models.
Now TV app unavailable
A YouView Box FAQ
You will no longer be able to access the NOW TV app on particular devices.