Well, I’ll try to explain how cookies and tracking codes work (and sorry for my English):
You have your tracking code in the URL when you send visitors to a poker site (like pokersite.com/?trackingcode=123).
When the visitor arrives to the poker site, they still have to keep your tracking code in some way, for example if the visitor visits more pages on the site before signing up or downloading the software. This could be done in two ways:
1. The poker site adds your tracking code on all internal links, for example: pokersite.com/promotions/?trackingcode=123, pokersite.com/about/?trackingcode=123. This is not used by many, since it requires the tracking code to be inserted dynamically to all internal links when pages are loaded.
or
2. When the visitor first comes to the poker site, they read the trackingcode-“parameter” from your link and store it in a cookie. This is the most common method, but it has one drawback: If the user has disabled cookies in his/her browser, your trackning code would simply disapear when the visitor enters the site.
Hope this explains a few things!