You are aware that roasted coffee is a perishable product? After roasting, it is at its best for just a few weeks. After just two months it has lost the best of its flavours, but for "bulk" coffee the taste is often considered acceptable for up to 18 months if sealed (at which point most cheap supermarket brands seem to have their "best by" dates.)

I am afraid you will find your 40kg of coffee degrade in quality over time.