Thanks Akash. Actually I did try the Microsoft licensing telephone number first, and after entering in various responses to narrow the focus of the call, I received a message that the licensing line was experiencing technical problems and was not operational
at this time.
Then you may want to wait until those technical problems have resolved.
My very unauthorative answer to your question is that there is no cost incurred on the SQL Server license cost; I've never heard anything about your operating system affects the license cost for SQL Server. (But I assume they need to pay for the OS upgrade
as such.)
Then again, in many of when you upgrade the OS, you also move to new hardware, and this can mean that you now have more cores than before, and that can definitely affect the license cost for SQL Server.
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se