Why isn't Windows 10 Pro accepting my serial number?

I upgraded to Windows 10 Pro a few months ago and now I keep getting the message Windows 10 Pro will expire soon, so I tried to re-activate Windows 10 Pro. But I keep getting error 0xC004F074. I've readed on http://www.thewindowsclub.com/what-happens-when-windows-10-expires that my laptop will restart every 3 hours from 18 July 2018. And 2 weeks later it wouldn't boot anymore. Does someone knows how to fix this?

I have found my serial number on the internet it worked a few months ago, but I've an activated (weird, then it should not expire, I think) Windows 10 Pro 1511 build 10586.1176 32 bit and x64 processor.