To get a YouTube premium code Visit the URL listed on your gift card or go to youtube.com/redeem.
Enter the code on your gift card.
Click Next.
Choose what you'd like to buy if you want to use your balance right away.
How to redeem Youtube premium code from Google Pay - FAQs
Sign in to your Google Account.
Go to youtube.com/redeem.
Enter the code.
Click Next.
Select what you'd like to buy and then select Google Pay as the payment method.
Click Buy to redeem your code.