Hack the system!
It should work for all KeyShot versions that have a Diffuse Pass and a Normal Pass available.As far as I can see, KeyShot is using the Intel Open Image Denoiser. Please, correct me if I'm wrong, but I got exactly the same results using it. So, what can we do with that information?
Start Blender 2.81a (with integrated Intel Denoiser) -> go to the "Compositing" tab -> click "Use Nodes" -> create the same node setup as in the image below. Hit "render" and save the image or the animation.
Don't forget to switch the color management from Filmic to Standard (marked in the image), to get same results as in KS.
Few remarks:
I'm not a big fan of the Intel denoiser for final images - it "kills" the details in your textures. But, it's still amazing for quick previews with very low samples.
You can try the NVIDIA OptiX AI-Denoiser instead. It is available as a plugin ("D-NOISE") for Blender too.
In any case, you'll have issues with animations and scenes that have Fur/Hair/Fuzz (name it). If you need good
animation denoising you should go with another solution like "Neat Video" (
LINK). This denoiser analyses multiple frames to keep the details.
Hope that helps.
P.S.: Blend file attached.