Cloud programs do not use serial numbers... you log in to your paid Cloud account to download & install & activate... you MAY need to log out of the Cloud and restart your computer and log back in to the Cloud for things to work
Some general information
Log out of your Cloud account... Restart your computer... Log in to your Cloud account
http://www.adobe.com/products/creativecloud/faq.html
http://helpx.adobe.com/creative-cloud/help/install-apps.html to install or uninstall
http://forums.adobe.com/community/download_install_setup/creative_cloud_faq
What it is http://helpx.adobe.com/creative-cloud/help/creative-cloud-desktop.html
Cloud Getting Started https://helpx.adobe.com/creative-cloud.html