No valid purchase date

Although it is usually required to have a "proof of purchase" when asking, for example, to remove activation lock on an iPhone, it is not always required for all services. However, it always pays to call ahead to see what your particular Apple Store or Apple Authorized Service Provider requires.

One option is to update the proof of purchase, but this most likely, not help you much.

You can certainly get this notebook serviced by Apple, but expect to pay full "out-of-warranty" costs associated with it.

Ref: Update your proof of purchase - Apple Support