Depending on how it's stored is your answer ... boveda 62% RH packs with minuim oxygen exposure in an airtight container can last up to 1 year but some processes can allow it to last fresh up to 2 years ... check out growing exposed series on YouTube it's all commerical grows in American and Canada explains how they do it professionally and how hone growers can make there products and own grows alot better ... if this helps please select me for answered question