Just go to the "conversion tracking" tab in google here they will give you a code you put on your website where the visitor ends up so you can see which keywords are giving you a sale or lead Very useful in optimizing your keywords and conversions!
Odds are you don't own the thank you page, so you'll have to pass the keyword through your landing page to networks backend reporting system. Just use some basic php if you know any. Example: your destination url in adwords is: http://www.your-site.com/your-landing-page.php?keyword={keyword} Then in "your-landing-page.php" make sure you pass the keyword variable along in your affiliate link: <?php extract($_request); ?> http://www.offer-site.com/index.php?sub_id=<?php echo $keyword?> Then when you log into your affiliate network, you can view the keywords that converted to sales by doing a sub_id report.