register i pad

You don't need to register an Apple Device. When it was purchased the serial number was registered to Apple's Systems for Warranty purposes. If it was recently activated, go to Settings > General > About and you can see the coverage end date there. As an FYI, Warranty Coverage began the day the device was purchased and left Apple inventory.

If you intend to transfer the iPad to a new User, you should first prepare the iPad properly - as doing so will both erase the iPad and remove the Activation Lock that will otherwise cause difficulties.

What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support