The answer is about the same time you can store leftover canned savory sauces, and that’s three or four days. Keep it refrigerated and in an airtight container. You can also freeze it for a couple of months. Since classic marinara is a versatile sauce and goes well with all kinds of dishes, you might like to make extra, so you can have spaghetti Bolognese one night and dip breadsticks in it the next.