check your account to verify your subscription is what you expect and to verify your adobe id, https://account.adobe.com
then, if your subscription is active, sign out and then back in to your cc desktop application using the same adobe id used to verify your subscription: http://helpx.adobe.com/creative-cloud/kb/sign-in-out-creative-cloud-desktop-app.html
if that fails, recreate your cached adobe credentials are stored in the OOBE folder
first, open your cc app > file > exit cc
then zip, or otherwise compress the files in oobe
then delete the uncompressed files.
restart your computer and sign into your cc desktop app or try starting a cc app (and you should be prompted to sign in)
Mac OS: \User\<user name>\Library\Application Support\Adobe\OOBE folder.
To access the hidden user Library folder see*
Windows: \Users\<user name>\AppData\Local\Adobe\OOBE folder.
To view the hidden AppData folder, see **