Often a recipe calls for less tomato paste than is in the can you bought. Not to worry - freeze the remainder in ice cube trays, using 1 Tbsp per "cube". Once frozen, put in a freezer bag and label. Keeps 2 to 3 months.
Save the rest of tomato paste in the can by wrapping approx one tbsp amts individually with Saran wrap then into a Ziploc bag and then into the freezer. When you need tomato paste, take one out and throw it unwrapped into the pot frozen and it melts almost immediately. Quick, easy and frugal!