Here's a sample clause that intertek uses:

4.5.1 We use the services of Google AdWords (including Google AdWords remarketing) so that we can place advertisements (called “Google AdWords”) on external websites for the purpose of drawing attention to attractive offers. Using the data gathered from these advertising campaigns, we are able to determine how effective individual advertisements are. We use this tool to show you advertisements that might interest you, to make our website more appealing to your specific interests, and to calculate our advertising costs in a fair manner.