When you have exceeded your limit of contacts (on either the Basic or Premium plan), you will get a notification in your FullContact address book letting you know. A few features will also be disabled when going over your limit.
When over your limit you will not be able to add additional contacts or sources. We will also stop syncing across all accounts which include Google Contacts and any read-only sources you have connected.
To remove this, you can either delete specific contacts, disconnect sources, or remove social contact sources. If you are on the Basic version of FullContact, you can also upgrade your account to the Premium to manage over 1,000 contacts. FullContact Premium version allows you to sync up to 25,000 contacts. You can find our pricing page here.