Normally WordPress doesn’t make it possible to manually update to a newer version of a Theme or Plugin through it’s Admin interface. However, there is a free plugin available (Easy Theme and Plugin Upgrades) that you can install from the WordPress Plugin repository to do this.
Your legacy installation API Key may show as deactivated even if your key has not expired yet. This is due to the legacy version being fully deprecated and having to be shifted to its own server.
You can download the latest version of AFP Legacy (1.3.4) from your API Downloads of your My Account page. But to enable you to update this in WordPress you’ll need to download the plugin mentioned above. Go to your WP Admin Plugins > Add New page and search for Easy Theme and Plugin Upgrades and install & activate it.
With this plugin installed you can manually update your AFP Legacy installation by uploading the Theme as you would if you were setting it up by default. Go to Appearance > Themes then select Add New from the top and choose Upload Theme.
You should now be able to successfully update to the latest version of AFP Legacy without getting an error WordPress normally gives “Destination folder already exists. Theme installation failed.” This plugin enables you to install the same theme or plugin manually via the WordPress admin interface.
With this you can activate AFP Legacy 1.3.4 and it will be able to communicate properly with the legacy license server.