If processed, packaged and stored correctly, the shelf-life of pure maple syrup can nearly be indefinite, especially in glass containers. To maintain optimal shelf-life, freshness, and flavor, syrup should be stored in a cool (room temperature or lower) dark place when unopened. After opening, syrup should be refrigerated. If stored properly, pure maple syrup will easily last 12 months, and in many cases many years. There is evidence of properly stored syrup lasting 50 years!