It will last for ages; unopened they are likely to last for years. Opened, several weeks in the fridge.
Hellymedic is right, the sugars in the pud mean high osmotic pressure & low water activity (it's an intermediate moisture food) so the number of organisms which can actually use it for food (apart from Moondog, of course
) are few, mainly osmophilic yeasts and moulds.
Here endeth the (food microbiology) lesson. Scoff away, lucky Moondog.