This post explains how to track the effectiveness of a partner link using the sub id.
Also you can add sub ID to all tools in the affiliate program.
You can create as many sub ID as you want and view reports on your dashboard, where you can find statistics for each sub ID.
This is especially convenient if you are distributing multiple links and actively pursuing success in the travel affiliate program. For example, if you are placing links or search forms in the text of articles, you can create a separate marker for each link and search form, which tells you which links are giving you the most conversions and purchases. Then you can concentrate on writing more articles of this type and thus gain more revenue.