Yes, it is legal to fly drones. But you must abide by Unmanned Aircraft System Rules (UASR) by the Ministry of Civil Aviation. All the drones weighing over 2 Kg and used for commercial purposes need a Remote Pilot Certificate, authorized by an approved organization at the (DGCA) site. From the official government portal, you will get UAOP and UIN numbers. Please go through the portal to understand the mandatory legal rules.