When a customer clicks your affiliate link (whether it's a text link, banner, or widget), their browser picks up a cookie with your affiliate code in it. If the customer makes a purchase on EdenFantasys while they have that cookie in their browser, you earn 20% commission on their purchase. The cookie expires in 180 days; this is where the "180 day commission period" comes from.
So, for that 180-day period, you earn commission on their purchases
unless something happens to the cookie. If the customer clears their browser's cookies ("deletes cookies") then your cookie will be deleted and you won't earn commission on their purchases (unless they click your affiliate link again). Similarly, if the customer clicks on a different affiliate link, the different affiliate's code will replace your code in the customer's browser.