Just like yogurt, homemade kefir can be kept for 2 to 3 weeks in the refrigerator in an airtight container. 
However, to extend its shelf life, avoid eating it directly from the jar. But, since it tastes so good and is so versatile, you'll likely finish it in a few days! 
However, to extend its shelf life, avoid eating it directly from the jar. But, since it tastes so good and is so versatile, you'll likely finish it in a few days!