GST on Export of Services by Indian Resident

One of my client who is resident of India is giving sevices of consultancy to Australian company and will be receiving Australian dollars in return for Invoice received in India.
He will be migrating to Australia for the next Financial year which will make him a non-resident
For the current financial year his receipts will not be crossing 20 Lakhs. Does he need to pay GST on the receipts received and does he have to take GST Registration?
pls advice.