You can install and activate the Softube plug-ins to two locations (three for Console 1 and its add-on channels).
Mac: To install on a new/second machine it is easiest to use Softube Central on the new machine. This should allow for installation and activation. Please note that you don't need to register your license code again, actually you can't as it has already been used.
Windows: To install on a new/second machine, follow the process on the Welcome to our new web page.
You will need to have a free activation, or will need to use an iLok dongle that you can move between machines to activate the new location.
Mac: To deactivate a license, use Softube Central.
Windows: To deactivate a license, use iLok License Manager.