"A long-running test is now rolling out for desktop queries: Google will no longer show ads to the right of its search results, with one exception.
Google is rolling out a dramatic change that removes ads from the right side of its desktop search results, and places ads only at the top and/or bottom of the page. At the same time, the company says it may show an additional ad — four, not three — above the search results for what it calls “highly commercial queries" - says Matt McGee in his article published on 19th of February 2016.
He also informs that "a Google spokesperson has confirmed to Search Engine Land that the change is now rolling out to all searches in all languages worldwide. Ads will not appear on the right side of desktop search results, with one exception: Product Listing Ad (PLA) boxes will continue to show both above and to the right of search results."