Studio One does not make you stay in a specific key. If I've missed the meaning of your question, please let me know. If you need the song key for your own preferences, I'd just add it to the track name, since it matters not in the DAW. It is a multiband compressor that allows you to pick frequency ranges to compress, and others to leave uncompressed. When used after a track is finished, it brings out a lot of what is lost when layering things. If you got the Professional edition of Studio One, there is an awesome treatment for mastering called "Multi-band Dynamics".
Sounds like you are entering a more unencumbered realm. If you are moving stems from one DAW to another, Studio One will let you do absolutely anything, no specific key since the tracks key can change at your whim, so it doesn't lock you into a set key. There may be DAWs out there that make you stay in one specific key, sounds awful, but Studio One breaks the chains and allows you to do anything. I don't do any electronic music so I don't understand your need to set up a key for a song. You can do anything in a track and you are free to use any key. I'm not sure there is a reason for doing it. "need to set song key eg A# or what ever key I need for each song etc."