Google has announced that it will be retiring the older version of AdSense for search and it is sending news to its users that it is time to switch to the newer version which is powered by their Google Custom Search, which has been offered for a while now to users.
When you pull up a search page and it shows “powered by Google” for the results page you are using the old version.
Google’s development team has made a number of updates and improvement over the past months and you will start to see you can access more advanced features. For example, with this newer version you will have features such as refinements and promotions. AdSense for search with CSE will give you more control over your search results without having to change the way you are currently earning money showing AdSense for search ads.
Google states that the existing AdSense for search box will work as it is now for just a few more months. They plan on updating their users further when it is completely retired. If you are looking to keep your current revenue during this transitional phase they recommend that you to update your code as soon as possible.