No activation codes are needed for expansion pack trials, simply follow the steps below to get set up.
Download and install the latest version of ToneHub by clicking here. Must be using version 1.10.1 of the plugin.
Once the plugin is launched, you will be prompted to log in with your STL Tones user account credentials. Now that you're logged in, make sure that the ToneHub plugin is activated.
Now click on the Expansion Pack you wish to trial, click Activate, then click Activate Trial. Your trial will now be active and you're ready to go.