WPSSO Core is multisite aware and provides settings pages in the network admin interface. You can install WPSSO Core as a "Must Use" plugin (in the mu-plugins/ folder), network activate the plugin, or activate it on individual network blogs (aka sites).

### License Management

Premium edition licensing can be managed network-wide by providing an Authentication ID for all network blogs, or an Authentication ID (possibly different ones) can be entered individually in each blog's Premium Licenses settings page.

> Please note that the WPSSO Core plugin and the WPSSO Update Manager add-on must be active on the default WordPress blog to get Premium edition updates. This is a requirement of WordPress, not the WPSSO Core plugin. WordPress uses the default blog (ie. BLOG_ID_CURRENT_SITE) to manage updates in the network admin interface, which means the default blog must be licensed to install Premium updates.

Blog ID 1 is usually the default network blog, but this can be changed using a few constants in the `wp-config.php` file. The default constants provided by WordPress during a multisite network install may look like this (this is only an example - your actual network settings may differ):

    define( 'MULTISITE', true );
    define( 'SUBDOMAIN_INSTALL', false );
    define( 'DOMAIN_CURRENT_SITE', 'example.com' );
    define( 'PATH_CURRENT_SITE', '/' );
    define( 'SITE_ID_CURRENT_SITE', 1 );
    define( 'BLOG_ID_CURRENT_SITE', 1 );

To change the network default blog ID, you must update the `BLOG_ID_CURRENT_SITE` and `PATH_CURRENT_SITE` constants for sub-folder multisites, or `BLOG_ID_CURRENT_SITE` and `DOMAIN_CURRENT_SITE` for sub-domain multisites (and `SUBDOMAIN_INSTALL` would be true in that case).