https://www316.americanexpress.com/iFormsSecure...
Got the below email from American express. Could be user specific, but as all Amex offers go, you can try enroll and see if it works for you. Make sure you enroll before you start spending.

https://www316.americanexpress.com/iFormsSecure...



Your usual spending can now take you for an exciting holiday!

Yes, simply use your American express Card for your everyday expenses, from shopping, dining, fuel, movies to bill payments and more, and get a complimentary American Express Domestic Travel hotel stay voucher.

What you do - What you get
Spend a total of Rs. 75,000 or more during the offer period on your American Express® Gold Card American Express Domestic Travel hotel stay voucher worth Rs. 6,000
OR
Spend a total of Rs. 40,000 or more during the offer period on your American Express® Gold Card American Express Domestic Travel hotel stay voucher worth Rs. 3,000

What’s more, the total spending on your American Express® Gold Card account also includes the purchases made on your Supplementary Card(s).
OFFER VALID FROM SEPTEMBER 1 TO SEPTEMBER 30, 2018.