How to See if a MacBook Has Been Registered
Registering a MacBook with Apple has several benefits. Your MacBook must be registered if you want Apple to repair it, or if you want to purchase extended AppleCare protection for it. Registering your computer also means that Apple acknowledges the MacBook as yours, which can be important if the computer is lost or stolen. If you're not sure whether your MacBook is registered with Apple, you can use a tool on the Apple website to check.
Click the Apple logo in the upper left corner of your MacBook's screen and select "About This Mac." Click the "More Info" button to open the System Information window.
Highlight the Serial Number of your MacBook displayed in this window, and press "Command-C" on your keyboard to copy it.
Open a Web browser and navigate to the Apple Service and Support Coverage page (see link in Resources).
Paste your MacBook's serial number into the "Hardware Serial Number" field, then choose your country from the drop-down list below. Click "Continue" to submit this information.
Click the "See your service and support coverage" link underneath the summary of your MacBook. If your MacBook is registered, you will see a green tick icon underneath the MacBook summary, and the word "Registered." If it isn't, you'll see an orange exclamation point and a prompt to register it.