Store bought Tomato Sauce in a glass jar.?

Once opened, even if kept in the fridge, I would toss it if you have not used by the end of day 4....now if you reseal it and pop it in the freezer, it can last up to 6 months. You can freeze it in the glass jar it came in but must partially thaw it before removing.

Tomatoes are acidic and acidic foods do not spoil as quickly as others if stored properly when opened.

I would NEVER keep opened tomato sauce for 3 months...and this is NOT a professional cook asking the question....

retired baker, home canner and home cook with 45 plus years of experience cooking. NO one I have cooked for has ever gotten food poisening, ditto me as well. Better to be safe than sorry. You may not SEE or taste that a food is beginning to spoil....why take the chance?

Spaghetti sauce is likely one of the few things that holds it's flavor when frozen. I made a huge batch of selfmade spaghetti sauce, put it in small Tupperware containers and used on or two a month for a year. The last was as just right as the primary. But to answer your question, you'll use it earlier than it goes dangerous.

It's good until it gets moldy, smells funny, or tastes bad. Tomato sauce is high in acid, which inhibits bacterial growth. I've kept opened jarred sauce in the fridge for a month with no adverse effects.

Check if they have preservatives

if it has class two preservative it would keep well up to 3 months

if it does not have them it would survive for 3 days depending upon how frequently you open it... more you open faster it would decay