API key is the name given to some form of secret token which is submitted alongside web service (or similar) requests in order to identify the origin of the request. The key may be included in some digest of the request content to further verify the origin and to prevent tampering with the values.
To get your admin key you should go to your profile settings
then click on 'edit' button
and then here you will be able to generate your API-key
If you still have any questions, you can ask them in comments or contact our support team