To activate your floating license, you must first download the Geneious Floating License Manager and install it on a server with a fixed IP address that all client computers can access. You will be prompted to activate your license during the FLM installation.
Floating License Manager Installers
Floating License Manager User Manual
Note: To install on MacOS, users must first download and install the Java 8 JDK from http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html. This must be installed prior to running the Floating License Manager installer.
Once the Floating License Manager is installed, download and install Geneious on each computer that will be using the software.
To connect Geneious to the Floating License Manager, start Geneious and go to Help->Activate License. Check "Use floating license server" and enter the address and port (default 27001) for the computer where you installed the Floating License Manager.
You must have both ports (default 27001 and 49630) open on the client machines in order to connect to the license manager.
Note: if you received your license key as a text file, you do not need the floating license manager. See this post for further information.