I tried again this morning and it's working. Sorry to have bothered you.
Yes. The purchase says it's registered to dammit2hell. I try to log in to the app to enter the key and get that error.
I picked up the pro version (PayPal donation) but when I try to log in to register the key in the app, I get an error pop up that says Error logging in: FirebaseError: Firebase: Error (auth/invalid-credential)