The best way to pause is to run MPlus not directly on your computer but on a virtual machine on your computer. Then you can suspend the whole virtual machine anytime you like and resume later where you have paused. You can even reboot your computer.
Further: If you are using linux, then you can suspend the mplus process running in a terminal by typing "ctrl" + "Z". To resume click "%" followed by "Return".
There are some further alternatives for more tech-savvy users, but those probably know them anyway.