I manage a nonprofit organization's website that integrates with PayPal for event pass purchases. I've noticed that buyers can keep older passes or items in their cart for extended periods and are able to purchase them even after we've altered the price or removed the item from PayPal. I'm interested in learning if there is an option to set cart item expirations, ensuring that the latest price is always applied or preventing users from purchasing items that have been removed.
Presumably you are using old PayPal Payment Standard buttons such as "add to cart", which are deprecated and no longer supported.
PayPal advises switching to a currently-supported integration, such as