LUT is not a hurdle if actually service has been exported.
Dear Sh. Vignesh Ji,
Your client has 'received payment' from a person/firm outside India. It is not in dispute. So service has been provided and not received (imported). So it is export of service.
However, it needs to be clarified on what account the amount in foreign currency has been received.
Normally when we give advertisement, we spend money. Here in addition to spending, money has also been earned. The 'possibility' of import of service is also here.
Therefore, correct and concrete and complete reply is possible only after going through the terms and conditions of the agreement or invoices. Sometimes terms and conditions are mentioned in the invoice.
Initially I asked for elaboration of the query.