Also, 2019 includes iCloud Document sharing.  This is a good way to accomplish what you are doing with Google Drive.  It prevents you from modifying the file on two different machines simultaneously if you are using a cloud drive.  It works best for iCloud as Apple has better APIs but it should also work for Google Drive. Even if you forget to be careful. 

The license is unchanged. You can use two machines as long as they aren't being used at the same time.