Sell-By Date Meaning

(idiomatic, by extension) Used to indicate that something, or someone, is old and out of date.

Example: The final date on which a perishable product can be legally sold to the public.
2007, March, As Blair contemplates the hereafter, Britain must endure a life in limbo, by William Keegan in The Guardian Online.
  Tony Blair insists on remaining in office well past his sell-by date - yet he can afford to go.