GST Applicability on Certain Transactions

You yourself in the Query Answered " Selling an Application to Google"
As per section 7 of CGST Act it's an supply.

And As per Section 24 of CGST Act , supply of goods or Services through E-commerce operator, mandatory required to obtain registration in GST & As per Section 25(3) the person once registered under this Act is required to comply with all provision of Act.

Hence you are required to collect & pay GST

@ Pankaj Rawat, i know tht person is not selling an application ..... a person is jus a 3rd party whho provide facility to convert google play coins into real money or voucher ..... kindly understand the query and then answer.