They provide a code that contains a 1499 Prime voucher which is equivalent to 1 Year membership fee.
No, you can add the code and the code is valid for the next 1 year you can redeem it at any time after your shopping edition ends.
Happy to answer your questions.
you have to use your 680 rs Prime voucher
Buy
https://amzn.in/d/bFlYRyH or
https://amzn.in/d/4WmzrtW and then you can add the 1499 Voucher.
On Amazon, max 1499 Prime Vouchers can be added not more than that.