If you have Ketu in your tenth house, this shows that in your past lives you had attempted to establish security through active and concrete actions in the world. You dedicated a lot of time to always doing something and being in motion. This pattern, however, did not provide you with expected security and left you unfulfilled.
If you have Ketu in the eleventh house, this means that in your past lives you had attempted to establish security through connecting with like-minded peers or large organisations. There has been an excess of social living and looking for validation. You also wanted to get awards, titles, and honours.
If you have Ketu in your twelfth house, this shows that in your recent past lives you had not involved yourself much with material world. You might have been focused on spiritual practices or less healthy activities of escapist addictions.