prevent multiple users sharing subscription access

I have React Native project. How do we prevent a user from creating multiple accounts and sharing the logins with different users

Example: Someone subscribe to the app. The have a monthly subscription and access to entitlement A

Lets say I have a login process that the user create and sign into an account (Account A). Now lets say that account A purchases an in app purchase and I am using the id of Account A as the sign in user for RevenueCat. If Account A purchase a subscription they will have access to content with Entitlement Pro. 

Now lets say that this same user logout. From my understand is that RevenueCat create an anonymous user and also create alias between the Account A and anonymous user. 

Now let say from the same device register a new account (Account B) if they press the restore purchase button RevenueCat will give access to this user and create an Amuse between the accounts

Now if a person share the login information of account B  to someone else with different device what is to prevent them from having access to the pro content. 

Its almost like a user can create multiple accounts restore the purchases to create alias then provide other users the login between all the created account to allow others access to pro content.