free trial member are given 45 days time period to buy Prime membership. if they buy membership within 45days of purchase then 30days within purchasing they will get their cashback!
see offer no 2.
if the Purchaser is not an existing Amazon Prime member and purchases the Product on Amazon.in, such Purchaser shall have 45 days to buy an Amazon Prime membership commencing from the date of purchase of the Product on Amazon.in. , the Purchaser will be entitled to receive cashback in the form of Amazon Pay Balance for the amount of the Amazon Prime membership i.e. INR 499 within a period of 30 days from the date of purchase of the Amazon Prime membership(such benefit hereinafter referred to as "Benefit 2")