Hi Roboabhishek,
This is your monthly tax invoice and signifies the fees already paid by you in the month of February 2018. It's only a notification mail. No more payments are to be done for the amount mentioned on your tax invoice.
Regards,
Zebpay Team
So it means that Bitcoin is legal in india to use it. As you are collecting tax for the transactions made, but their is no clear picture about Bitcoin state in India.