I have 2 articles here if you are interested.
https://www.investopedia.com/financial-edge/0712/what-happens-when-your-credit-card-expires.aspx https://www.creditcards.com/credit-card-news/herigstad-credit-cards-expiration-date-1294.php Bascially 2 things:
1) Wear and tear. Our credit card is actually quite complicated, holding a lot of information. But as time pass and with frequent use, the card itself will spoil as they are not built to last forever. Expiry date gives the bank a chance to give you a new card. Your credit card account remains active.
2) Prevent fraud. I think it is rather self explanatory for this.