There is no such ambiguity in the definition of "paid". Cue separately disclosed the trial users (8M) from the paid ones.[1] So there are actually 46M Apple Music users.

[1] https://www.reuters.com/article/us-apple-music/apple-music-h...

I mean if they include people who didn't actually pay in the category of "paid" members, that would be a lie, no matter how you look at it.