2006 New York Code - Written Promise Expressing Past Consideration.

 
    § 5-1105. Written  promise expressing past consideration. A promise in
  writing and signed by the promisor or by his agent shall not  be  denied
  effect   as   a   valid   contractual  obligation  on  the  ground  that
  consideration for the promise is past or executed, if the  consideration
  is  expressed  in  the  writing  and  is  proved  to  have been given or
  performed and would be a valid consideration but for the  time  when  it
  was given or performed.