While reviewing your AdWords Campaigns report in Google Analytics, you see that the report lists campaigns that were terminated before the selected date range.
This is not an error. Google Analytics stores the traffic source of an original visit in the __utmz cookie that it writes to the visitor’s browser and refreshes the source with each visit – except if the returning visit is direct.
When a visitor returns to your site by typing your URL directly into the browser or accessing a bookmark saved in the browser, the __utmz cookie does not override any of the more specific traffic sources below that it recorded on a previous visit:
• organic search
• Autotagged AdWords campaign
• referral from another website
• any inbound link containing Google Analytics campaign tags
This feature in Google Analytics is quite useful, since it usually makes sense to attribute a returning direct visit to a more specific original source.
Remember to add campaign tags to inbound links from emails, or resulting visits will count as direct and you therefore will not be able to credit your email campaigns for any visits or conversions at any point in the visitor lifecycle.