...
A Channel is a virtual representation of a Video Device or an NDI®5 NDI® Source within the network. Depending on the number of inputs, you can configure one or multiple Channels.
...
After configuring a Channel, you have to enable it by clicking on the checkbox next to the Channel name. The Channel can now be used by the Just In Mac Lite application. When quitting and relaunching Just In Mac Lite, previously activated Channels will still be active, so there is no need to open the Just In Mac Lite Configuration panel and activate the Channels again.
...