Accessing Sage on different networks with 2 licenses simultaneously

SUGGESTED

I currently have 2 licenses for Sage 100 set up with license on a desktop and the other on a laptop.  I can access sage on both computers simultaneously if I am in the same network using wifi.  The laptop is used by an employee who travels to jobsites or works at home.  How can both computers access sage simultaneously at two different locations (meaning two different networks).  What is the most economical solution for a small business?

Thank you