I Pureed chipotle peppers in adobo and placed the unused portion in a sealed container in the fridge. How...?

Months. We do it all the time.

If you add some vinegar, quite awhile. I've done that just to have around to put in chili, salsa, etc. I'm at the end of a jar that's been in the fridge for about a year. The acid in the vinegar is a natural preservative. Add 1/4 of a cup of apple cider vinegar.

The best way to store them is to: take each pepper and place it separately on parchment paper on a cookie sheet, divide the adobo evenly on top of the peppers, freeze, and then place them in an air-tight container in the freezer. They will last a lot longer that way!

I again am in agreement with "Jimmy d", I often have them but do make sure to put them ina new container and out of the can, they keep for weeks, covering them is not necessary unless the adobo sauce is low, a bit if hot sauce or tomato sauce even, in a pinch even some ketchup, nice for when you have a hot dog.

Quite awhile, I would try and use it up in a week, though!