Get your API key creating a project/app in https://console.developers.google.com/project, then inside your project go to "APIs & auth - APIs" and turn on the "Google+ API", finally go to "APIs & auth - APIs - Credentials - Public API access" and click in the "CREATE A NEW KEY" button, select the "Browser key" option and click in the "Create" button, now just copy your API key and paste in Social Count Plus options.
