I had some upgrade issues for my version, but going the Steinberg Download Assistant route fixed it.

Check it again in like a month or so to be sure, any trial time expires and/or simply try actually using some pro features )

Dunno if this is a bug, as Steinberg wouldn't toss out free Pro versions out there. But tbh I am not too sure as well, because I updated it some time ago, rarely ever used it, due to doing MIDI orchestration only, but never had issues like license warnung about trial expirations in the meantime. Steinberg offers one combined installer for all editions afaik, but usually it should install the appropiate version automatically. You might also run SL standalone for checking which edition is actually installed, as this works with the One version as well. For me it clearly says 'SpectraLayers One', although I am still on 8.0.10 and not. If you have Cubase open right now, put SpectraLayers up on any audio event you have and check Help -> About. Steinberg usually specifies very clearly, which version you got in the 'About' tab. Which should not work unless they offer a trial for that one. If you can unmix more than vocals from an audio event, you have SL Pro installed.

Cubase 11 pro spectralayers