What may be easiest for you is to Google "Cakewalk Command Center" and download that. Then log into CCC the same as you would with your account. That is the automatic installer and would be the easiest way to verify/install in your case. Platinum has a lot of products with it, and the CCC will show everything that it applies to (some older products will not appear, so you must download those manually from your account).

Yes looking at that offer it was not the Lifetime update offer, just the standard day to day upgrade offer. 
So you paid for one year of upgrades and that time limit has expired. 
It only means you will have any updates available to you after that year ended. 
That version is yours and will still install and run. 
 
Example; I bought Sonar Professional Feb 11 2015 on the upgrade offer from X3. 
In the mean time I then upgraded to Platinum. So my 1 year expired and this is what shows on my product page. 

 
But I can certainly download and install the software and it is still fully functional. It's just stuck at that old version. 
 
Install Command Center and it should show. There have been glitches with people finding Sonar in Demo mode but Command Center seemed to solve that issue. 

Thank you for clarifying.  I was thinking there was a subscription service to use the software like Adobe.  When I open the program it doesn't seem to be in demo mode, so I guess the subscription expiration just applied to new updates.  I think I will be ok with a slightly older version as I'm a hobbyist noob (unless they added some groundbreaking features in the updates). Will the software still be usable if the server dies?  I used to play around with Sonar back when it was just a physical disk in a box.
 
Sorry for the panic, oops!  I didn't realize the company had been dissolved until I logged in to download Sonar yesterday.  Since the customer service email wasn't set up, I thought they just left everyone hanging.  I'm glad there are still people sticking around on the forums, and super responsive ones at that!  It's good to know Sonar will be picked up by another company. Too bad for Cakewalk, but I will be interested to see what BandLab does with things.

no worries. I understand why your panic would set it.
Glad its all good now.