Great question — answering as the UphillTech team:
Google Analytics is not Affiliate Tracking tool, you have to be the website owner in order to track its pages. You can track your affiliate landing pages using GA If you'll open a GA account and register your landing pages you'll be able to see in: Standard Reporting -> Sources -> All traffic the breakdown of the traffic sources Standard Reporting -> Sources -> search will show you the keywords that were used. You can find more information in regards here
Full answer by Nir Alfasi: https://webmasters.stackexchange.com/a/28902 (CC BY-SA 3.0).
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