I bought airpods pro & applecare at costco - do I have to register applecare or is it done automatically?

It might not be a bad idea to check if they completed the paperwork.

Check Your Service and Support Coverage by clicking here --> https://checkcoverage.apple.com/

if necessary:

Click on this link to read how to 'Update your proof of purchase' --> https://support.apple.com/HT202703

To update your information contact Apple Support by phone. Tell the advisor that you need help with your Apple Limited Warranty or AppleCare plan expiration date.

Here’s what you need when you call:

- Your AppleCare agreement number

- The device serial number

- Your sales receipt