Kushal
The license is decided by you or more likely by your employer.
The point I'm making is that by putting code up with no copyright and no license, anyone who uses it could later be sued by your employer for copyright breach. You also may be breaking your employment terms by posting it if you have not been given explicit permission by your employer.
This is why I would always recommend users use libraries like Paho, where there is a clear copyright, license and the history of the code is known and verified.
Best
Paul