I use tomato paste and canned chipotle chiles in adobo sauce quite often with my cooking.  However recipes that I use rarely call for using an entire can (even the small cans).  I just hate wasting food…so I’ve started freezing what I don’t use in the recipe (paste/chilies).  I just dump it in a freezer bag and when my next recipe calls for that ingredient, I simply cut off a chunk of how ever much I need.