I could swear I saw this question answered here when VEPro 7 dropped but can't seem to find it again so forgive the repeat. I know VEPro 6 and 7 can't exist on the same computer. On my daw I have a dual-boot system with OSX 10.10.5 on one partition and OSX 10.13.6 on the other. I have VEPro 6 on both partitions; my preferred working partition is the High Sierra one where I work in Pro Tools 2019.6.
To keep compatibility with older stuff I've worked on I need to keep PT 11.3.2 and that means keeping OSX 10.10.5 PT 11.3.2 and PT 2019.6 can't exist on the same partition. So I would keep VEPro 6 on that partition. I also have several 32 bit only plugins that I run in that partition.
Everything else I do in High Sierra and PT 2019.6 and I can run VEPro 7 there replacing VEPro 6 and being able to take advantage of the new stuff in VEpro 7.
The question becomes: can I have license assets for VEPro 6 and 7 on the same Vienna key? Or would I have to have them on separate Vienna keys? I have two Vienna keys from when I ran a two computer system (now down to just 1 computer). Sad part is I did try VEPro 7 when it came out but can't remember what went on with the license assets on the dongle.