An LUT remains valid for current financial year from the date of its submission. Example- If LUT was furnished in FY 2021-2022, then the date of expiry of the validity of such LUT is 31st March 2022. Therefore, you need to file fresh LUT for FY 2022-2023.
If the goods for export are not exported within three months of Date of Invoice issue, then the Exporter is liable to pay GST along with 18% interest within 15 days according to Section 50 (1). Also in case of payment for services are not received within one year for which the LUT has been submitted, the exporter is liable to pay GST @ 18% within 15 days. Failing to do so will lead to withdrawal of LUT facility and on subsequent payments, it can again be restored.