To get the YouTube Premium membership for free via Flipkart, launch the Flipkart app and sign in by using your mobile number. After that, visit the SuperCoin zone from the menu and look for the poster YouTube Premium for 2 months with 50 SuperCoins.
Tap on it and click on the orange button 'Get Using 50 SuperCoins'. Select Yes to continue and on the next page, a voucher code will be displayed.
Tap on it to copy and launch the Chrome browser. Visit youtube.com/redeem and paste the code. Then, hit next and click on the 3 months free option. Finally, make the payment '0' using debit or credit and enjoy.