You will need a Google search API key to run EzineArticles campaign.
You may already have access to a Google search API key but in case you don’t, it is fairly easy. You can follow this link to get your API key.
Google will ask you to select an existing project or offer you the option to create a new one.
Select a project or create a new one. That was all you needed to do. Within a few seconds Google will provide you your custom search API key.