You cannot pause an exam.
On the real PMP Exam you will have 4 hours to answer 200 questions. If you take a break, then the clock "keeps ticking". We have built The PM Exam Simulator to reproduce the "real" experience as closely as possible, so therefore, there is no option to pause an exam.
If you only have a limited time to take an exam (for instance, you have 1 hour over lunch that you want to spend taking a "short" exam) then use the Quiz mode. Here you can select 50 questions which need to be answered in 1 hour.