Tell why winston is not killed each time he is tortured

In 1984, we learn that when Winston shows that he does not agree with the ideals of the Party, he is captured and tortured. However, he is not killed. The main reason for this was the fact that killing Winston would imply that the Party does not have the absolute power that it claims to have. Killing Winston would be equivalent to admitting that some people can have different views, and it might lead to him becoming a martyr. Instead, the Party uses torture in order to show that no one can escape its power and exercise free thought.

we need more information in order to answer.