"On the Account Permissions tab of your Google Account, you can see a list of third-party sites and applications. These are sites and applications to which you've granted permission to access your Google Account, and you can see on this list to what parts of your account they have access. For example, you might have downloaded an app that helps you schedule workouts with friends. This application might have requested access to your Google Calendar and Contacts to suggest times and friends for you to meet up with," informs Google's help center.
Google shows your Android and iOS devices at the top of the page. My Nexus 7 tablet was listed 3 times, so I clicked "Revoke access" next to the entries that include: "Inactive - We haven't seen activity from this device for at least 60 days."
If you see some services you no longer use, click "Revoke access". You'll be asked for permission the next time you use them.
{ Thanks, Florian K. }