In the past older version of Flash the installers never disappeared after an install. Versions 11.3 and 11.4 the installer disappears after the install is complete.
The process we have is to install software off our network rather than download softwarefrom various websites. We have downloaded and saved installers and they are persistant, not disappearing after an install (other than Flash Player).
Joshua M. Peterson
I'd recommend signing up for our distribution agreement which you can find here: http://www.adobe.com/products/players/flash-player-distribution.html
Once signed up, you'll be given a page that contains installers that you can then distribute on your network. For previous installers, please see our Archive page.