This policy setting allows you to configure whether newly installed add-ons are automatically activated in the Internet Explorer 9 browser. Any add-ons that were activated in a previous version of Internet Explorer are considered to be the same as newly installed add-ons and are not activated when the user upgrades to Internet Explorer 9.In Internet Explorer 9 add-ons are defined as toolbars Browser Helper Objects or Explorer bars. ActiveX controls are referred to as plug-ins and are not part of this definition.If you enable this policy setting newly installed add-ons are automatically activated in the browser.If you disable or do not configure this policy setting newly installed add-ons are not automatically activated in the browser. Internet Explorer notifies the user when newly installed add-ons are ready for use. The user must choose to activate them by responding to the notification using Manage Add-ons or using other methods.
Windows Components\Internet Explorer
At least Internet Explorer 9.0