Get a tupperware container with a lid. Put a moist napkin in the bottom of the tupperware and then place your cans of snus you are using on top of the napkin. Close lid, refrigerate.
I personally double it up, meaning, I put the snus with a moist napkin in a sealable ziploc bag first and then put that sealed bag in tupperware with another moist napkin. My snus has stayed very fresh for a very long time this way, and I can have many open cans at once. It's great cause you can take whatever you need for that day, put it in your temporary can and then seal it up to tomorrow. It limits the contact with dry air and you only need to remoisten the napkin every week or so.
I personally double it up, meaning, I put the snus with a moist napkin in a sealable ziploc bag first and then put that sealed bag in tupperware with another moist napkin. My snus has stayed very fresh for a very long time this way, and I can have many open cans at once. It's great cause you can take whatever you need for that day, put it in your temporary can and then seal it up to tomorrow. It limits the contact with dry air and you only need to remoisten the napkin every week or so.