I can help with Nice and Witness, unsure about other recording apps. First, the guidelines were written to help because it is not as simple as you might hope. The fact is, in the hands of less skilled folks, what might seem clear to many could easily be twisted into a demand for free license due to confusion. First, insight into use...
When TSAPI creates an association for basic services, a license is consumed. Two basic types of associations, domain controllers (station, hunt group, vdn monitors), and call controllers. When an existing association exists for that AES server/CTI Link, additional client requests will use the existing monitor, thus will share the license. I recall, up to 8 clients can establish a monitor association on a given device, thus up to 8 apps could share a license.
HOWEVER...R4.2 adds some trusted license types that are not shared, these are for Avaya apps to allow license to be sold at lower cost (or free) without giving away for other apps. The confusion comes from the fact that this is a bit complex, so they give general advice that wont catch you short...but, technically it works to share a lic and nobody will refuse support over it. Bottom line, buy what you need, but if you don't know for sure, go with the guidelines so you don't fall short.
DWALLIN comment above is spot on, so here is how the recorders use the additional lics for recording channels:
Nice monitors all agent stations, all times, all configs. Plus, it uses a full time lic on rec channels UNLESS doing DMCC All Calls in which Service Observation is done once using DMCC (thus 0 TSAPI lics for this mode). For selective DMCC (SO or SSC), selective DS1, one license will be used per recording channel at all times the system is running. For trunk/station side taps, no license is used for recording channels.
Witness has several configs, some use no TSAPI. When TSAPI is used for the rich call tagging (monitors on agent stations, hunt groups, vdns), it is like Nice, all stations, all times.
The Witness bulk recording uses no TSAPI for recording channels. Bulk record uses Call Info service in DMCC for tagging calls, and uses button commands to park the observer on the agent set at startup. So, in bulk record, channels never use a license, agents, hunts might use TSAPI in some cases when more info is required.
For Witness conference and selective recording, each concurrent recording will use a license, plus the agent stations etc. In conference recording, TSAPI tells the system about calls on agent stations, business logic decides when to record, and finds a channel to add. Since you could potentially use all channels, you want 1 lic per channel, but will see use based on concurrent recordings.
Use will be constant in all but selective/conference Witness recording.
TSAPI Advanced is now licensed on per CM basis, recording never uses advanced. When a link is opened to CM, CM reports it's vital info like release and server type. The first time an app invokes an advanced request (predictive call, route select or selective listen/hold), TSAPI will look for a small/med/large based on the server type from startup. Once it is cleared for use, it is never checked again. The Advanced Users are also still used on a per transaction basis, but use is so short that it is rare to see the Advanced Users in use. About the only time you might see them in use is with predictive calling on large scales where many calls are launching concurrently.