The Google+ API is the programming interface to Google+. You can use the API to integrate your app or website with Google+. This enables users to connect with each other for maximum engagement using Google+ features from within your application.If you need a Unique Google Plus API key then just follow the below three steps.
Step 1 Go to https://code.google.com/apis/console#access
Step 2 Now you will see below screen; just click on creating project option
Step 3 Now you will see many google Api’s, Find the Goole+API. So Activate the one that you need for your projects. we will activate Google Plus API project.
Step 4 Click on OFF Button for make it ON
Step 5 Now Click on API Access Tab
You will see your unique API key that you can use on
Use the Highlighted Key as your Google API Key.