I ordered 4 Sir Walter Scotts 15 gram tins. Was wondering how to handle. Can I open all of them and place in fridge when I'm done pinching from them? Or should I open 1 or 2 and use as needed an place in fridge? How long can they be out of the fridge for? Most time I carry the snuff I'm using in my pocket. How do I know if they went bad? Just mould? I feel like I need to use up an open tin as quick as I can but not sure if I'm just over worried. Anything else I should know about artisan snuff? Thanks.