The NBT you have paid can be set off against the NBT payable based on your sales. This is similar to input VAT.
In the NBT return you can mention the input NBT amount in cage 3 (allowable tax credits) in the previous method (Now in RAMIS system).
This is mentioned in Sec. 6 of NBT Act as "Where any person to whom this Act applies, utilizes wholly or partly any goods purchased from a manufacturer registered for payment of tax under this Act or imported by himself, in the manufacture of goods liable to tax under this Act, such manufacturer shall be entitled to tax credit in respect or such tax paid on such goods in proportion to the value of goods manufactured by such person which are liable to tax under this Act"