Activation Issue after I have been activated since the late 1980's????

The was an update to CbB last night too. Was the update to CbB applied?
The current support page is here.

What is the exact message displayed and the error code? Did you also update CbB to build 31?
You can see the error code in the message displayed or in the about box.
 

Noel,
Sorry to get so excited.  It just hit me at a very high pressure time with major bucks riding on it.  After I calmed myself down, I jumped back to my copy of Sonar Platinum (still installed, of course) and got through the day.  The following message in a maroon box came up with CAKEWALK written vertically on the left side.  The box msg reads:
Exclamation Mark ! in triangle.
Demo Mode
You are currently running in Demo Mode due to a problem with activation.
Please contact support. (4-99)
 
It just caught me so off guard because some hours before it was running perfect.  It has been running perfect since I put the 3.06 stuff in with absolutely no problems and all my previous stuff has been available to me from Sonar Platinum.  Just caught me off guard, just didn't expect it from 3.09 as I expected it was a maintenance update.   I have learned my lesson about updates before a session.  Let's call that lesson learned.  Sorry or the alarming message. 
 
To Cactus:  Your msg was absolutely from someone who has apparently never been in a situation like that.
I used my backup of Sonar Platinum to get through.  Thanks for offering zero solutions, but rather chastisement.  Noel, thinking about trying the update all over again, but will wait to hear from you on this one.  Thank you.
 
 
 
G
M
T

 
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I installed bandlab assistant 3.09 and did the update that came with it.  Upon just trying to get into the Cakewalk program again, the same notification came up, yet my info on the program says legal.  I run everything in my audio setup as administrator since I am the only one on this machine.  The bandlab says I am up to date.  In the Help pulldown for info on the program, I am currently at 24.04.1 Build 31 [2018.04]- x64.  In the bottom of that black box info pulldown from help it says again:  Demo mode -  Please update with bandlab assistant.  Bandlab assistant says I am up to date.

promidi

Make sure you have version 3.09 of the installer - I say this because you can't tell if you have simply by looking at the filename of the installer.  All versions have the same filename.  Version 3.09 has an exact file length of 45,587,528 bytes

To check the version click the gear in the upper left of the BA UI and select "App Version" from the menu

Checking installers is not the question though. The only thing that matters in this case are the running versions. From the information reported by the OP:
BA is at 3.0.9
CbB is at 24.04.1 Build 31
OS is Win7 SP1 (there may need to be more info provided but this request would have to come from BandLab)
 
I believe these are the critical pieces support needs for this problem. I was just trying to help the OP flesh out his report. It is up to BandLab to sort this out.