router has no software key

i have RB433 with ROS 3.11 it was working perfect for almost a year till it restarted, then it says your router doesnt have a valid software key,so plzz anyone could help me.
thanx in advance

contact to support@mikrotik.com

M.

I had this exact problem.

I unfortunately could not re-install ROS as instructed as Ether1 was dead, so netinstall wouldn’t work.

The question is why does a working router suddenly lose it’s key?