Purchase history

If you have a copy of the order, assuming you bought your device at Apple Online Store, contact them using this link:--> https://www.apple.com/contact/ and ask for a copy of that document.

If you ordered and bought it somewhere else, contact the reseller.

Regards

Giulio

On iPhones, purchase history is related to apps, music, or other content you bought from AppStore and/or iTunesStore.

For the iPhone, you a should have (and keep in a safe place) the receipt/invoice reporting your devices Serial number or IMEI.

Regards

Giulio