A 'cookie' is a small piece of data sent from a website and stored in the user's web browser while the user is browsing. Cookies were designed to be a reliable mechanism for websites to remember pertinent information (such as items added in the shopping cart in an online store) or to record the user's browsing activity (including clicking particular buttons, logging in, or recording which pages were visited in the past).
When a user clicks on your affiliate link, this action will place a 'cookie' in the browser that they used. That cookie helps us identify if a customer who made a purchase came from your affiliate link. Our cookies last 7 days. We found that most purchases happen within the first 7 days hence why our cookie window is only that long. However, our cookies are not product specific, so if your customers buys any course (even the ones you didn't promote to them) within the 7 day cookie window you will earn a commission from that purchase.
For example, if Customer A clicks on your affiliate link using Firefox on her laptop and purchases a course we will attribute that purchase to you as your cookie is in her browser.
If Customer B clicks on your affiliate link using Google Chrome, but makes a purchase using his phone, there would not be a cookie in place because the phone is a uniquely different device. The cookie was stored on his Google Chrome browser so you will not get credited if Customer B purchases a Udemy courses on his phone.