At the end of the play, Kate tells Chris not to worry about anything and just to "live."  Just before this, Chris has told Kate that she (and everyone else) must realize that they are part of a global community and that they have responsibilities to all other people in that community.  Chris tells Kate that her failure to feel responsible means that Larry has died in vain.  Joe then commits suicide, and Kate wants Chris to know that he should not feel responsible for Joe's actions.  Kate does not want Chris to "take it on [himself]."  The play overall questions the issue of personal and global responsibility and how much of a role individual people play in their responsibility towards others.  Kate's response to Chris exemplifies the tension in this issue.

Kate's last word to Chris is "Live." What do you think she is telling Chris to do? What do you think Ann and Chris should do? 

Just after Joe Keller commits suicide, Chris appears to be burdened by what his father has just done.  Chris has just finished telling Kate that she and others must realize that they are responsible for other people and that our actions affect others around us.  Kate does not want Chris to feel responsible for Joe's death, and her telling Chris to "live" suggests that Joe's actions were payment for his own wrongdoings in life and that his suicide had nothing to do with Chris or the family.  Kate does not want Chris to be burdened by his father's decision.