Copy the application from your Applications folder on one machine to the Applications folder on the other.  Or you can download it again on the 2nd machine from here: 

https://support.quickbooks.intuit.com/support/ProductUpdates.aspx

The main issue is how you use your company file on two different machines.  The only safe way is to copy it to your travel machine before you leave and then copy it back once you return.  That works fine but you have to be sure to only use it on one machine at a time or you will lose your work.