To enable Hide If No Products plugin and configure it's settings find in NOP admin under FinestCommerce plugins plugin settings
(path: /Admin/HideIfNoProduct/Configure)
If you have multi-store, then you can configure plugin based on store view.
Plugin settings:
Hide Category If No Product - select to apply automatic hiding rules for categories;
Hide Manufacturer If No Product - select to apply automatic hiding rules for manufacturers;
API Key - enter API key to make API protected;
Cached Data Update Interval - set time interval in minutes for updating cached data regularly;
Cached Data Forced Update Interval - set time interval in minutes for forced cached data updating (forced update is done if there was manipulation with any product, category or manufacturer).