If you have SE3 then “Yes for Sonic SE, but no for Groove Agent SE”. If you are still running HALion SE2, you can upgrade it for free. Just download it from here and install it. It will replace SE2.
You can use HALion Sonic SE 3 with another 64bit DAW, or even in ‘stand alone mode’, but you must have your CuBase, Nuendo, Dorico, or HALion dongle plugged in (or on soft-eLicenser if supported by your version) to access the HALion SE content packs that shipped with your Steinberg host(s).
What I mean by this is that the Sonic SE 3 player is free, and you can register basic eLicenser keys for all your systems upon request, but the HALion content that ships with various Steinberg products are not. So, you’ll need to have your CuBase/Nuendo/Dorico dongles plugged in if you want to use the Basic HALion content that shipped with your Steinberg DAW. Of course this also applies if you use extra HALion libraries like Steinway Grand, Symphonic Orchestra, Dark Planets, etc. SE3 can play such content from any DAW, or in stand alone mode, but you’ll need to make sure their dongles are plugged in.
Sonic SE 3 works with any 64bit host, and you can register for a free key that is optional to install if you already have a CuBase/Nuendo/Dorico/HALion eLisencer key on the target system. The free key is meant to allow anyone to use 3rd party libraries developed with HALion 6.
I.E. I could make a library myself with HALion 6, share it, and then people out in the wild could use it with the free Sonic SE player in the DAW of their choice. People who already have something like CuBase or Dorico installed on the target system will not need the ‘free Sonic SE key’ to run my libraries, as their CuBase/Dorico dongle covers it, but persons who do not own a Steinberg DAW could register their free key and still use my library with HALion Sonic SE with any 64bit DAW they like.
If you wish to use Sonic SE 3 with a 32bit host, I believe you will need to bridge it somehow, or run it in stand-alone mode and connect it via Virtual MIDI ports. My understanding is that there is no 32bit version of Sonic SE 3. jBridge, Bidule (via rewire), and VEP come to mind as methods to bridge plugins if you need to get SE working with some 32bit DAW. Later in this post I will also provide some links for setting up virtual ports, which would make it possible to trigger sounds of SE in stand alone mode from any DAW running on the same system or LAN.
The full version of HALion Sonic 3, and HALion 6 work with any 64bit DAW, or in stand alone modes. They include and unlock all of the SE content that ships with stuff like CuBase. Again, the latest versions are 64bit only. If you need to run them in a 32bit DAW, you’ll need to bridge, or roll back to HALion Sonic 2/HALion 5. Note, registered H6/S3 users need to apply for a special license key (for free) to roll back from Sonic 3/HAlion 6 to earlier versions. The reason one needs the key addend to roll back, is because the newest HALion stuff has an option work without a usb dongle (can be placed on the software eLicenser upon the first installation), but the older stuff will ONLY work from a USB dongle…hence the need for two keys if you need to roll back.
As for Groove Agent SE…
I am not aware of a version at this time that runs directly in non Steinberg hosts. If you use it often, consider buying the full version of Groove Agent. Of course the full version of Groove Agent can be hosted in non Steinberg Hosts, and it will come with all of the SE content, plus a whole lot more.
It is possible to use a virtual or rtp MIDI port as a bridge from your secondary DAW to an instance of CuBase in the background (or running on another PC), but I’m not sure if that is going to be worth the trouble. If you are on a PC, you can find free software for making virtual MIDI ports, or for setting up MIDI over LAN here. If you are on a Mac, then you can set up virtual ports through the native Mac core audio system.
When it comes to syncing and bridging multiple DAWs together, I personally find the free ReaStream plugin quite helpful. I.E. I can run something like CuBase on one PC, Reaper on another, sync them up, trigger sounds in either/or/both over the LAN via rtp, and get audio streams between the two over the LAN via ReaStream. I.E. I could have a lean instance of CuBase Elements running in the background with nothing but a couple of Groove Agent SE tracks, trigger GA via virtual MIDI port, and divert a stream back into the Primary DAW via ReaStream.
CuBase can also be a ReWire Master. So, it is possible to sync up any DAW that can be a ReWire slave with CuBase, and trigger sounds hosted in CuBase via Virtual MIDI. In this case you would not need ReaStream, since all audio sources are going to get piped through the CuBase Mixer. This is actually a pretty common practice with apps like Sibelius and Finale.