motion blur, volume and particles , I also noticed it doesn't support decals .
Motion blur works when you export to ORBX, and render out in standalone. The sequencer ORBX exporter will generate the motion vectors during export, providing motion blur.
The other features are on the feature list.
I also would like to upgrade it to my subscription but I don't know how .
Licensing is a bit of a mystery for me aswel. You should be able to use the studio and enterprise tiers for the unreal plugin if you have a studio or enterprise license.
If you dont have a license you can just get one from shop page.