I'm guessing you mean that you want your slide to transition after the last on click animation WITHOUT a further click. Sadly there's no way to achieve this from the GUI.

There is a trick which can make it LOOK like this happens which will work with many slides. It's a bit of work but I think it's the only way.

DUPLICATE the slide to get two identical slides.

Slide One remove the LAST animation but leave transition on click
Slide Two Remove all EXCEPT the last animation and set this to 'with previous'.
Give this slide an auto transition.