How should I record and track a user status in firebase?

I'm trying to track whether each user is a premium member or not. I'm using Firebase authentication.

Do I need to use Firebase-Admin to do this (using .setCustomerUserClaims). At the moment I'm just using Firebase/app.

Is there a better way?
Perhaps I could upload the User's UID to FireStore along with a Premium Boolean value, and when the user logs in pull the premium boolean status from the Firestore? But this would require an extra fetch from the database each time the user logs in, whereas the Firebase-Admin solution would only require one interaction with Firestore, upon registration.

This is my first project and I'm hesitant to use Firebase-Admin. Is this a legitimate concern?

Thanks!

Both storing the subscript status as a custom claim and storing it in Firestore are valid options. Neither of them is pertinently better than the other. It all depends on your use-case and other needs (stuff we can't know, and you might not even know yet either).

Things to keep in mind:

• Custom claims are sent with every request to the server.
  This is great, because they're readily available with each request.
  This is not great, because it means you're adding the info to each request.
• Custom claims are refreshed when the ID token is refreshed, which happens automatically once an hour.
  So if your subscription status change needs to be detected before the ID token is auto-refreshed, you will need to make an additional API call.
• Storing the info in Firestore means that you need to perform an extra call to look it up.
  On the other hand, it'll always give you the latest value when you look it up

I'd typically use a custom claim for something that is either status or changes rarely (e.g. whether somebody is an admin), and use Firestore for things that do not fit that bill.