The entire concept of clarified butter IS to make it last longer. Once you remove the milk solids, butter can be cooked at a higher temperature without burning, and can be stored at higher temps for a much longer time. I only know this intellectually, not from experience. Yakuta, where are you?
Butter also freezes well, and salted butter lasts longer in the fridge than unsalted (the entire purpose of salting butter to begin with).
I personally freeze 3 sticks of butter when I buy a pound (there are only two of us in the house) unless I'm planning something where I know I'll be using more. I actually prefer salted butter, but buy unsalted because it makes hubby feel better somehow.
I've kept butter in the fridge for a week and a half with no problem if it's properly wrapped and sealed (going bad isn't as much a problem as picking up other flavors). I've actually never had butter go bad, period, and suspect I've had sticks of it in the fridge longer than that. Not recommending it, just talking personal experience.
I have a thing about tasting all my ingredients before, during, and after cooking. That way I know if it is safe. Of course, I'm not thin. lol.