For additional soundbanks to work inside the HardKick plugin, they need to be activated to your main HardKick license key.
When activated they are connected to your personal HardKick plugin license.
A sound bank can only be activated once.

In case you can’t find your original HardKick license key, click the settings button in the top right of HardKick.
You will see your license key in the top of the panel. Right click to copy the license key to your clipboard.

Notice: some users have reported a security notice while activating. If this happens to you please use a different browser or log out / clear your browser cache. A fresh activation session will work. We’re working on a solution

Contact Psylus Audio support in case you experience issues.