Hi and welcome to Arturia forums.
The question is can i use Analog Lab with both Keystep and Beatstep simultaneously?
I believe there are ways to do this in standalone mode. But it might depend on what you exspect to do. Perhaps someone in/ from the the keystep and beatstep forums or from Arturia can tell more about this to be completely certain. But i believe it's possible. I would say it should be.
In a DAW you can use multiple instances and the possibilities the DAW have to use different controllers for different tracks.
Furthermore if in the future i wanted to connect Beatstep with a hardware that connects with USB midi only, would it be possible and what kind of setup is required? In this setup i would like again to control parameters of other hardware with the knobs of Beatstep.
I think there might can be limitations in controling hardware. But i don't know. I don't have the controllers.
This is only about the hardware controllers functionality. Perhaps it's better to ask in the relevant forums or contact Arturia directly. You can be lucky Arturia answer here.