Hi @tinybigstudio
You can read all about including ACF here:
http://www.advancedcustomfields.com/resources/getting-started/including-acf-in-a-plugin-theme/
There is no way to prevent a user from copying out the ACF plugin, but that is just something that can’t be policed.
Thanks for your concern, but you don’t need to worry about it too much.
Thanks
E