Is FIRC required for Export of services under Letter of Undertaking

Hi,
Is FIRC required for Export of services under Letter of Undertaking?

I am running a software service export company. I am going to take GST registration this year and I want to know applying Letter of Undertaking for export is enough for the exemption of the GST payment? Whether I have to produce/upload FIRC at the end of each month or each year?
 

Regards

Muthu