I have the same problem identified here:
http://forums.adobe.com/thread/1024884
I am running Windows 7 on a new Dell Vostro, have a subscription to Creative Cloud, have never installed a trial version of the software, and recently installed Premier Pro. The first time I try to run Encore, I get the two screens shown in that thread and repeated here:
"Adobe Encore CS6 cannot run in trial mode. Please relaunch the application and provide a valid serial number."
"Adobe Premier Pro. Provide a serial number."
I had previously got the problem identified here:
http://helpx.adobe.com/premiere-pro/kb/missing-sequence-presets.html
Following the recommendations fixed the problem, but still Encore has the same issue.
When I access this URL:
https://lm.licenses.adobe.com/
I get the message:
"Congratulations! You have successfully connected to Adobe License Management Server."
It appears this is a common problem, but there does not seem to be a common solution. For example, here:
http://forums.adobe.com/message/4677807
and
http://forums.adobe.com/message/4589055
I checked and have no "Hosts" file.
Further, here:
http://forums.adobe.com/message/4677888
I have found that waiting or rebooting the PC does not fix the problem.
Lastly, I tried that proposed here:
And that did not work either.
Illustrator, Photoshop, and Premiere Pro all work fine.
So, what is the solution?
Update, 2012-11-06. I spent 30 minutes on a chat session with Adobe support. The support person told me emphatically that Encore is not part of Creative Cloud and can be obtained only by buying Premiere Pro and not from the Creative Cloud subscription. To prove the point, the support person pointed me to this page:
https://creative.adobe.com/apps
Now on that page, Adobe has done something clever and stupid. If you view the page with XP (for example), it does not show Premier Pro because Premiere Pro works only on a 64 bit OS. If you view the same page under Windows 7 it does show Premiere Pro. I think it would be better if Adobe showed the application (possibly greyed out) with a note that it cannot be installed on the PC that is viewing the page. Well, I was having the chat on my laptop (running XP) and I guess the support person was also on XP so the case was proved!
But I sent him a link to this page:
http://www.adobe.com/products/creativecloud/tools.html
However, the support person told me I needed to contact sales. I called them and asked the support guy to wait on the chat session until I had an answer. The lady in sales said that Encore is definitely included in Creative Cloud. But as I was about to relay that information to the support person, he ended the chat session!
The pleasant lady in sales said she would transfer me to phone technical support. I was on hold for 60 minutes and had to quit to go and do a task.
Perhaps this will be resolved and I shall update this thread ...