The GB Instruments are part of GB so they can only be run within GB. Some third-party instruments are available in both plug-in formatsâ€”which will work only within a DAW (like GB)â€”and standalone formatâ€”which will open on its own as an application. If an instrument is available as a standalone then yes, you don't need to open GB to use itâ€”after installing it the standalone version will be found in your Applications folder and will have its own Preference window where you can make MIDI & audio interface settings. But if it's only available in plug-in format, then you would need to be in a DAW (GB) to use it. In the case of Helm, apparently it comes in both plug-in and standalone formats, so you should be able to open & run it as an application, outside of GB; other instrument plug-ins may or may not offer that same capability..