Actually placing keywords at the end of the article is helpful for ranking higher. But, Google is smarter than us.
If you place related searches keywords at the end of the article, you will have to face serious problems which include Drop of rankings, Ban from Google search engine etc.
So, it is better to place the related keywords in the body of the content or in the meta description to rank higher.
If you have any doubts, Reply and I will give you answer as fast as I can.