I'm running windows 10 pro (1803) and have updates defered for 365 days to allow other people to find the bugs for me. I actually moved up to this level on 10/7/19.
The Windows Update page declares
"Your version of Windows has reached end of service. We recommend you update to the most recent version of Windows 10 to get the latest features and security improvements."
and but also tells me that I recently got the latest Win 10 Update with new features and important security updates. To my surprise I am still getting security updates (last on 28/1/20).
I'm not sure why it is not upgrading now I am past the 365 day period for the next upgrade unless it is counting from 10/7/19.
All I can say is that in this case the crap M$ upgrade system seems to be working in my favour as I have no desire to actually upgrade from where I am as long as I get the security fixes!