Mobility license is a restricted license for wireless endpoints only.
Mobility upgrade converts Mobility licenses to regular Base, Plus and Apex licenses.
Since you already have regular license types (which cover all endpoit types - wired, wireless and VPN), neither mobility nor mobility upgrade is required.
License are consumed when features specific to the license are used for a given endpoint. So a remote access VPN endpoint with AuthZ/AuthC and using profiling would use one Base and one Plus license. If you added posture or MDM integration services for that endpoint, it would consume an Apex license as well.