RevGenetics Advanced NMN has undergone an internal 10-week stability study under harsh heat with flying colors. Advanced NMN was stored in an environment of 104 Degrees Fahrenheit consistently for 10 weeks. Our Advanced NMN went from 99.7% to 99.5% purity in those 10 weeks (close to 3 months). We suggest keeping it in a room that is 76 degrees or lower to be assured the NMN will last 1-2 years.