Your licence works on two computers at a time. To use it on a third, take one of the others off first.
Open Studio, then Licence..., and choose Take this computer off.
When you activate, Listn Studio shows Take a computer off with the computers your licence is on. Choose the one you no longer use.
On the old computer, open Licences in Listn Hub and choose Free this computer on Listn Studio's licence.