A jar of strong-brewed coffee - how many days should you store it?

I have this habit of brewing a very strong jar of coffee, like 8 cups, and store it in the fridge. I would add hot water whenever I feel like an “instant coffee.” One jar would last many days.

The question is, is coffee supposed to last that long? How many days should it be kept before throwing it away? I’ve never heard of coffee going “rancid” or anything like that..