Arrakis the applications are still installed on your computer. Please see http://forums.adobe.com/message/4396277#4396277?tstart=0 for information on how to download and install the Adobe Creative Cloud applications.
In regards to needing a serial number this is not necessary. You will need to sign in with your Adobe ID tied to your subscription however. Once signed in the Adobe applications will periodically check your subscription status. You will want to make sure that you have regular access to the Internet to allow your applications to remain activated.
Finally there is no need to remove the previous versions of the Adobe Creative software you currently have installed. You may even want to still utilize these applications as you begin to adjust to the new workflows available in our latest Adobe Creative applications.