You can keep opened pasta sauce in the refrigerator in its original jar, with the lid tightly on, but a tomato-based sauce will only last a handful of days this way.

Pesto sauce will last up to two weeks, while Alfredo sauce will only last about four days in the fridge after opening.

If the sauce has not been warmed, keep it in its original jar, but if it has, store it in an airtight container to retain freshness and avoid cross-contamination. 

You can also freeze sauce for up to 3 months. If it has a rancid odor, moving bubbles, or mold, the sauce has spoiled, and you should discard it immediately.