proof of purchase

基本解释

Researchers asked music buyers to prove that they had proof of purchase.
他們要求所有購買音樂的用戶都要出具他們的購買証明。
Apple has reviewed your proof of purchase and your request to update the purchase date in our records.
蘋果已經讅核了您的購買証明和您的要求來更新我們的記錄購買日期。
Please note that your name has to be clearly readable and that we can't process requests without proper proof of purchase.
請注意，您的名字都必須有明確可讀，我們無法処理不正確的購買証明的要求。

They are notorious of not servicing something if they do not have the original proof of purchase.
ENGADGET: HDTV Buying Guide: Extended Warranties HD
It comes with a signed box and a copy of proof of purchase from Harry Winston, dated May 23, 1980.
FORBES: 30.52-ct. emerald-cut diamond sold for $3.3 million.
That liability usually ends up as Treasury debt parked at the Federal Reserve in custody for foreign governments, the proof of purchase for billions of dollars in extra U.S. imports.
FORBES: Congress Messes With China While Sen. DeMint Eyes The Dollar