is_plugin_active_for_network( string $plugin )
Determines whether the plugin is active for the entire network.
Only plugins installed in the plugins/ folder can be active.
Plugins in the mu-plugins/ folder can't be "activated," so this function will return false for those plugins.
For more information on this and similar theme functions, check out the Conditional Tags article in the Theme Developer Handbook.
Path to the main plugin file from plugins directory.
True if active for the network, otherwise false.