This page describes general information about the API and Touch Portal.
Plugins are placed in the plugin folder in your Touch Portal user data folder. The location of this folder is different per OS. Given that the plug-ins folder inside the .tpp file is named "TouchPortalTools", that would result in;
When a user creates an action a full copy is made and stored locally. There is no hard reference to the plug-in. This means that the action will be loaded and shown even if the plug-in is not installed. This does however mean that if the plug-in is not installed, the action will most likely not work. This also means that when you change the nature of an action as the developer, the changes will not be made in already added actions for the user. You need to re-create the action to see the new changes.