他们说它在3个小时后过期，您可以通过联系客户服务将其扩展到72.使用过它，但从未与他们联系，所以...

They say it expires after 3 hours, and you can extend it to 72 by contacting customer service. Used it, but never contacted them, so...

文档: https://developer.paypal.com/docs/classic/api/merchant /SetExpressCheckout_API_Operation_NVP/