export realisation in rupee

Kiran (Partner) (148 Points)

02 January 2019  
Hello,
My friend is regular GST supplier within India, recently he got oversea order from Middle East country.
The invoices will be raised in Indian Rupee and the export proceed is realised in Indian Rupee..
how should he deal with GST, can he export on LUT.
My concern is , since the inward remittance is not in freely convertible foreign currency, will he have complication during assessment

please guide