A-Star Green Lemon is a generic clear lemon and lime soda made by the brand A-Star and it is available on the website IndiaMART and possibly at some local stores in India.
It is sold in bottles of 250ml, 600ml, and 1,5 liter and it is sold alongside A-Star Cola and A-Star Orange.
The drink is called Green Lemon because there are many generic lemon-lime sodas called like that in India probably referring to lime being green and similar to lemon.