Some tins come with a plastic cap that slips back on, if not, kitchen/ catering supplies should have one, used for cat/ dog food tins etc. It will keep for months in the fridge, but just watch the metal of the can doesn't start to corrode, particularly where the can opener may have scratched the tin. If that's the case then just transfer it into a plastic container, minimise the amount of air and it should be good to go for a few months. :icon_cheers:
Edit: As per Aaron's advice, perhaps not the best idea, I just watch for corrosion, some tins have a plastic internal coating and they're the ones I'm thinking of when I suggest capping. If not, then transfer into plastic or glass.