Question about data integration with another app


I am trying to setup a node red application to also display in a UI, my data coming from my gateway to the lora server. I am using mqtt and I am listening to the topic “gateway/mygatewayid/rx”. This is working well for a single node but if I need to add some more end devices how can I distinguish from which device the data are coming from ? Maybe if I register all my devices to the LoRa app server and then listen to the correspoding topics it would work but I don’t want all of my devices to be registered.Is there any thing that differentiates my devices’ payloads?

Thank you.

All device data you can see in this topic: application/+/+/+/rx