Most store bought sauerkraut is pasteurized and not fermented.
The store bought sauerkraut is almost always pasteurized which kills any potential bacteria including the good bacteria that makes the sauerkraut the most healthy.
Store bought sauerkraut is still healthy but homemade non pasteurized sauerkraut is the healthiest because when made properly the homemade sauerkraut will contain the good bacteria and probiotics that benefit your health.
Canned Sauerkraut can and does eventually go bad even when kept sealed up.
However as long as the canned sauerkraut remains sealed and never has been opened and the canned sauerkraut has no rust on the can or holes or dents then the canned sauerkraut is good for at least 10 years if not longer.
It's best to eat the canned sauerkraut well before 10 years though because the quality of the canned sauerkraut degrades.
Once you open the canned sauerkraut it will only last for up to a week unless you put the canned sauerkraut into a tightly sealed jar.
When you keep the sauerkraut refrigerated it should last up to 6 months if it's kept sealed.
Sauerkraut can and does eventually go bad in the fridge.
When sauerkraut is kept in the fridge or refrigerator the sauerkraut will last for up to 6 months.
Sometimes the sauerkraut may last a few months longer than 6 months in the refrigerator as long as the sauerkraut container remains tightly sealed and the refrigerator temperature remains constant as well.
It's best to eat the sauerkraut within 6 months though and then have fresh sauerkraut for later.
The sauerkraut is not something you want to keep for too long.
But as long as you keep the sauerkraut sealed and refrigerated it should be good for at least 6 months.
If the sauerkraut has any mold in it or the sauerkraut smells bad then throw it out to avoid getting sick.