[Linda Buquet]

Nope - you get credit if they buy the 1st visit on any affiliate program. The cookie only comes in play to track future visits that don't come directly from a click on your site but buy wekks or months after finding the merchant and clicking on your link. So you get paid wither way providing the surfer still has the cookie and providing they didn't visit another affiliate and click a link after your cookie was set. In most affiliate programs the last cookie gets the sale.
But that also means if the surfer clicked another link before yours, but then clicks your link and buys OR buys later, you get the commish if you were the last affiliate clicked.

Hope this helps and makes sense.