Most everything in your fridge is that way. From your hotdogs, lunch meat, left overs. Anytime you break the package you should consume it within a week. (note this does not apply to freezing). If you buy a large amount of something that you dont think will get used within 3 days to a week then re wrap it and freeze it. Almond milk has a two month shelf life from the pasteurization im guessing it says ultra-pasteurized somewhere on the container. The cool thing about milk is that spoilage bacteria will render the milk unpalatable before pathogenic bacteria will make it unsafe to drink. In the restaurant industry they use colored stickers and they mark every container with an open date or discard date. And about 1 week they toss it.