You can use Rootsmagic on more than one computer. Maybe not literally at the same time, but why would you want to. To transport your database from one place to another, I'd just put it on a flash drive. You can put it on two flash drives if you want to be sure!
You can also put your Rootsmagic store folders on a flash drive, and your pictures will be there as well.
Keep in mind that if your other computer has different drive letters for things Rootsmagic won't be able to find your images unless you edit them, which you should be able to do globally by changing the C:// or whatever letter it is.
The whole point of services like Onedrive are to use files for more than one computer, so I'm not getting why that would be a problem, but these services have so many problems and shortcomings it didn't take me long to give up on them altogether.