The pure Nullsoft Winamp was from 1997 to mid-1999 with AOL having Winamp under it's ownership until 2013 (technically until mid-January 2014) when it was sold to Radionomy (who then were bought by Vivendi but then bought themselves back under the guise of Audiovalley).
So that time with AOL covers v2.5 when it became free after starting out as shareware through to v5.666 along with the maligned WinAmp3 period. So that's whole a lot of not doing much but still producing releases for almost 15yrs. Winamp (& SHOUTcast) were sold before Verizon did it's thing with AOL.
-dro