The common image of concubines in fiction and in historical works is one of beauty and youth. But what happened when they began to age? Were they bounced out of the palace and into the gutter? Palmed off for marriage to a man of a similar age? Or just executed?
As it stands, your question is incredibly broad, covering thousands of years across the whole world and thus falling under our No Example Seeking rule. Could you please narrow down your focus a bit?