Unlike some software that only requires the key, SoundSource requires the associated with the purchase.
Once a valid license key is applied, several restrictions are lifted: soundsource license key work
License keys are specific to major versions of the software. You can identify your version by the starting characters of your key: Keys start with SS6_ . SoundSource 5: Keys start with ZLAT- . SoundSource 4: Keys start with TCAT- . Unlike some software that only requires the key,
: Enables your Mac's physical volume keys to work with hardware that usually doesn't support them, like HDMI monitors or DisplayPort audio. System-Wide Effects soundsource license key work
After purchasing from Rogue Amoeba: