How long would dunkin donuts last?

You need to keep them warm. If their temperature drops below the temperature of the air they will start to absorb moisture from the air. The moisture from the air will crystallize the sugar and harden the doughnut. 14 hours should be possible if you place them in a well regulated warming drawer. The temperature of the drawer has to be very low to avoid melting the frosting or gradually overcooking the doughnut.