This is after I have activated it by running the updater first and then sonar.  It tells me it is activated.  Then coming back the next day, opening Platinum, it says it is running in demo mode.  What's up with that????

Is it still running demo mode after you stop/start the app?
Not that it should matter but do you have an internet connection?
Try running Command Center again...

From CCC try "Launch" if still in Demo mode you may need to contact Ryan Munis (via PM).

Where is launch?  I activated by running CC and starting Sonar.  Then rebooted and started SONAR.  It said running in demo mode.  Who and how do I contact?  Thanks.

I experienced the same problem, Platinum started in Demo mode. I think it was solved when I opened the Command Center, highlighted Platinum and on the page clicked the "launch" button. This started Sonar in the regular mode. Platinum was no longer in "Demo" mode. Hope this works for you.  
If this problem still exist, PM - Ryan Munnis [Cakewalk], he helped a user that had the same problem

Same problem with my installation on Windows 8.1 x64 PC. Nothing helps. :(

mauryw
Where is launch?  I activated by running CC and starting Sonar.  Then rebooted and started SONAR.  It said running in demo mode.  Who and how do I contact?  Thanks.

It's not likely; but, If you are like me you might have failed to install the Command Center thinking that the "Welcome to Command Center" screen instead was the CC!  "Install" bottom right of the screen needs to be executed.

I randomly get demo mode, but only when I start Sonar from it's own shortcut instead of CC. Closing and opening it again has fixed it so far.

You MUST start Platinum from the Command Center?  Or you do it that way as a workaround because it keeps starting up in Demo mode?
 
I worry because I plan to upgrade from X3e on Thursday (its Monday).  I want an icon on my desktop, click it, and the DAW opens sans problems.

With recent update now everything fine, thank you.