Factory Made - 2008 Postage Stamps was released on:
USA: 7 March 2011
Postage Due - 1924 was released on: USA: 17 February 1924
Sunshine Factory - 1984 was released on: USA: 1984
Factory to Field - 2010 was released on: USA: 27 December 2010
The Song Factory - 1920 was released on: USA: 28 March 1920
Columbia Bicycle Factory - 1897 was released on: USA: March 1897
It depends on the issuing authority. The US has not devalued postage stamps since 1862, which means anything issued since then can still be used for postage. Other countries have invalidated stamps as of certain dates or events. Check with you local postal authority for specifics in other countries.
A postage stamp isn't 'dated.' If it has dates on it, they typically reflect something to do with the history of the what is pictured on the stamp. And stamps can be used at any time.
Food Stamps - 2010 was released on: USA: 2010
Postage Due - 1924 was released on: USA: 17 February 1924
American Stamps - 2009 TV was released on: USA: 15 February 2009
Generation Why - 2010 Postage 1-8 was released on: USA: 31 July 2010
The Factory - 2014 II was released on: USA: 2014
Factory - 1993 VG was released on: USA: 1993
Sunshine Factory - 1984 was released on: USA: 1984
Chocolate Factory - 1952 was released on: USA: 1952
Death Factory - 2014 was released on: USA: 2014
How Do They Do It - 2006 Liferafts Mind Control Stamps was released on: USA: 4 October 2012