I can use the trail version of Adobe, but can't use Encore without the serial number. Pretty frustrated when you pay monthly.
As far as I know, you are not supposed to need a serial number with the Cloud... so this may be a question for that forum
Cloud Forum http://forums.adobe.com/community/creative_cloud
Or, maybe for the special install forum - Chat http://www.adobe.com/support/download-install/supportinfo/