I would likely go OneCNC or maybe Sprutcam if I was starting over.
I have VisualMill 6 PRO now and it is great however they went to an annual subscription for the new version and I will not get into annual subscriptons for the dozen times a year I use CAM. To be clear - the ONLY reason I would leave VM at this point is the subscription and if I had full time use for CAM I would gladly pay it and stay with them.
The VM dongle is no concern to me, just close the program, take dongle to other PC, open program, can't get much easier. I would hope the OneCNC works the same way.
RUNNER - You CAN use SolidWorks on the 3 computers in your scenario. All you need to do is login to your license manager and un-license that machine, go home and then license that copy. This is the same method used when you build a new computer and want to transfer. If you forget to un-license the PC then format the hard drive (so now it is impossible to un-license) you better hope you are still on subscription because you will have to call tech support and have them wipe that license from their database.
www.integratedmechanical.ca