Help finding product key via Steam

[Reikanji]

Hey guys, silly question for me, but I can't think of how atm.
I want to get my product key so I can login to Altitude through the standalone app. and not Steam. Vapour ID is: 4529dba9-3408-480f-ad8e-cc6089b5119c

I can't remember my E-mail, or even if I registered with one, so seems to make sense to ask here.
How does one get the product key through a Steam copy of Alti? (RMB>show game product key isn't available in Steam UI)

Thanks!

[Premier Stalin]

I'm not sure this is possible. They are separate clients, and they use different login systems.

You can check the various other threads in this section requesting the same thing, but I'm pretty sure this is the case.

Although if you ask nicely karlam might give you a key I guess.