Answer: 

That all depends upon how old it is at the time of purchase. A fresh bar of soap is soft enough that you can make a dent in it with your finger. At that time it contains more water than if it is allowed to age, dry and harden. The longer you allow my soap to dry before initial use, the longer it will last. However, that also makes the scent less apparent. The scent will return when the bar is wetted for use. If you allow the soap to dry, a complexion bar can last up to a year! Of course, soap used in the shower by multiple people will consume faster.

To increase the life of your soap, never allow soap to sit in a soap dish where shower water can hit it. Use a soap dish with ridges so the soap is not in contact with the water and can dry between showers.