MacBook Air warranty update

Check its serial number using this site: Check Your Service and Support Coverage - Apple Support.

FYI you are not addressing Apple on this site. No one here can update its serial number in Apple's records. To contact Apple use the Support link below.

If you need to correct your Mac's purchase date, you must contact Apple by phone:

Update your proof of purchase - Apple Support

"To update your information, contact Apple Support by phone. If you have an AppleCare plan, have your AppleCare agreement number, your device's serial number, and your sales receipt ready when you call."