It's unclear precisely what you intend. Programming for Pan & Zoom (or the Ken Burns effect) covers the entire clip - from Start to Ending positions.
If you want to extend (freeze) the end take a snapshot of that frame and add the snap (which will be in the Images bin) after the clip.
Or use the Motion effect to individually animate scale and position...
Set the first scale and position, then click the green + sign to create a keyframe (dot). 
Move the cursor to where you want the freeze to be, then adjust the desired ending scale and position.
Now preview the effect by dragging the cursor from left to right. The action should freeze at the final keyframe/s.
For more on animation, look here.
An example that starts at the top-left and is sized/positioned to full-screen in the middle of the clip...
test.mp4