Flash Player disappears

After installing and verifying the installation of the latetest 64bit Flash player, my system works well.  Sometime later I go to another website that tells me to install the lastest Flash.  When I go to http://helpx.adobe.com/flash-player/kb/find-version-flash-player.html to check again, the app in not installed. This has been repeated more that a dozen time. 

How do I resovle this?