MEIS Scrip

1. NO
2. NO

1.) MEIS Licences are freely transferable Duty Credit Scripts. They are exempted under GST vide Notification No. 35/2017 C.T. (Rate) dtd. 13.10.2017.
Therefore no GST is applicable on Sale or Purchase of such licences and thus, the question of Reversal of ITC does not arise as you have utilised the same for payment of Custom duty.
2.) You can show the Purchase of MEIS Licence in GSTR3B under the head of Exempted inward supplies with the amount paid on Purchase of such Licence. Regarding utilisation of such licence for payment of Custom duty, there is no need to show the same in GSTR1 or GSTR3B

1 No
2. In GSTR 1 , under table 8 & in GSTR 3B under table 3.1(c)