This seems to be a homework question, and I doubt seriously that it is
about Word, since it's a standard B-school-type topic. Out of the kindness
of my heart, I will point you to
http://www.quickmba.com/marketing/product/lifecycle/, which is the first
hit if you Google for "product life cycle." Now, go and sin no more (learn
to do your own research).
--
Suzanne S. Barnhill
Microsoft MVP (Word)
Words into Type
Fairhope, Alabama USA