Do not buy the mach3 software yet.
The settings will not be on the board within your router.
You will need to enter your settings (parameters) in the Mach installation on your new computer. Depending on the cnc board within your router there may be additional settings which relate to a motion controller.
If you are starting from scratch then bear in mind that Mach3 is now obsolescent and Mach4 may be a better choice.
The installation manual for Mach4 can be found here;
https://www.machsupport.com/wp-content/uploads/2014/05/Mach4%20Installation%20Manual.pdfAnd the Mach3 installation here;
https://www.machsupport.com/wp-content/uploads/2013/02/Mach3Mill_Install_Config.pdfOnce you have your router working then consider buying the Mach software.
Tweakie.