How long does Menopause last?

I was confirmed that I'm going through Menopause early just like my mom. I'm 46 and had a Hysterectomy in 2000 which left me with just 1 ovary. I'm taking Black Cohash & Soy to help with the night sweats and other wonderful effects of it but I'm hoping that it doesn't last too long or is this something that will last forever?