When you embed content from Google+ on a webpage, article, or other external location, you must follow the Google Terms of Service, the Google Developers Site Terms of Service, and the following policies:

Make sure that the location on which you embed Google+ content adheres to the Google+ User Content and Conduct Policy. For example, do not embed Google+ content on a webpage that promotes illegal activities, contains sexually explicit material, or includes malicious code.

– Do not embed Google+ content in a manner or context that would violate the Google+ User Content and Conduct Policy. For example, do not embed content in a way that results in harassment or bullying of others.

– Do not embed Google+ content within advertisements or for other commercial purposes.

– Do not alter or obfuscate embedded Google+ content or any of the surrounding presentation, material, or code associated with the embedded Google+ content.

– Do not attempt to discover the identity of users who comment or take other action on embedded Google+ content unless the user consents to share his or her identity with you via a Google-approved authorization procedure.

– Do not use, sell, or transmit to others any data obtained from the embedded Google+ content, including data related to the user’s interaction with embedded Google+ content. For the avoidance of doubt, this prohibition includes, but is not limited to, any use of pixels, cookies, or other methods to recognize users’ clicks on embedded Google+ content, the data of which is then disclosed, sold, or otherwise shared with other parties.

Google may analyze your use of embedded Google+ content, including to ensure your compliance with these policies and to facilitate our development of tools for embedding content. By embedding Google+ content on a website, you give Google permission to review and analyze that website.

If we are notified that your use of embedded Google+ content violates any of these policies or the Google Terms of Service, we may review and take action, including blocking you from using embedded Google+ content on your website. Please note that we may modify these policies, and that we will post notice of modifications to these policies on this page.

via Embedded Content Policy