Tried Blind Match for MicroObservatory finder images. Went to Astrometry.net and logged in. Went to MyProfile and got my API. Copied it and pasted into Observatory/Preferences/Accounts/API key. It is there, but an attempt at Blind Match still tells me I need to get an API key. I will try restarting Observatory.
After restarting Observatory, check if the API key is still set in the preferences. It is securely stored in keychain.
To clarify that last part. If you see the alert "Observatory wants to use the login keychain" when you open the Accounts Preferences, or after entering the API key, you'll need to enter your password, so Observatory can put the API key and/or ESO login credentials in your keychain.
Observatory does not ask to use my keychain. It does nothing when I open preferences and paste in an API.