To check if the plugin is enabled we work with a two-step mechanism.
First, you have the filter ‘mainwp_activated_check’. This filter will return true if the main plugin is activated. Because sometimes our main plugin is activated after the extension plugin is activated we also have a second step, listening to the ‘mainwp-activated’ action. This action is triggered by MainWP after initialization.
In the example above you can see that the child-plugin calls the function “activate_this_plugin”, this function will include the initialization of your own plugin.