You can gain the following benefit by duty payment using the DEPB license.
1- If you are getting the License in Discount rate, that amount is a income to us. ie some time the depb license holder may provide discounted rate of its actual license amount.
2- If you are an import you have to pay VAT without getting any vat input. by purchasing depb license, you must pay the vat amount, you can use this vat input for paying the vat amount.