Your CID is used by the EAN accounting teams to identify sales and pay you commissions. It is also used with our Chameleon template in order to identify your account and apply personalization attributes like colors and logs.
Your apiKey is used to authenticate your requests to the EAN API. It is used to tell us if you are approved for production and if you are a known developer.
After you have developed a program using our API and gained production approval to "launch" from EAN, we will place your apiKey in live mode and associate it to your CID. This allows you to actively sell EAN rooms and earn commission.
To create a new apiKey if you already have a CID, please see this page: http://developer.ean.com/docs/getting-started/