Well for future users with similar questions I have found a good answer. I found this on the danstar website "Nottingham will rapidly lose activity after exposure to air. Do not use 500 g or 10 kg packs that have lost vacuum. Opened packs must be re-closed, stored in dry conditions below 4°C, and used within 3 days; 11 g sachets are not vacuum packed but are flushed with nitrogen gas to protect the yeast"
My dog smells like PineSol and he insists on sitting on my lap.