Is it a per User or per Device License and it is Perpetual?

It's not per user, and it's not strictly per device (if you're treating a single PC or laptop as one device). A licence is required to activate/enable the USB receiver, where each licence is tied to a specific receiver.
If, for example, you have 2 receivers then you can purchase the 2 matching licences and install these 2 licences on each presenter's PC and laptop (each licence can be installed on multiple PCs, and a single PC can have multiple licences installed on it). Setup and tested correctly, a presenter could use any receiver without checking it's the right one. Licence files are not perpetual, they are usually set to expire after 1 year from purchase.