npx expo install @clerk/clerk-expo expo-secure-store

// App.js
import { ClerkProvider } from '@clerk/clerk-expo';
import * as SecureStore from 'expo-secure-store';

const tokenCache = {
  async getToken(key) {
    return SecureStore.getItemAsync(key);
  },
  async saveToken(key, value) {
    return SecureStore.setItemAsync(key, value);
  },
};

export default function App() {
  return (
    <ClerkProvider 
      publishableKey={process.env.EXPO_PUBLIC_CLERK_PUBLISHABLE_KEY}
      tokenCache={tokenCache}
    >
      <RootNavigator />
    </ClerkProvider>
  );
}

import { useAuth } from '@clerk/clerk-expo';

export function useProtectedRoute() {
  const { isSignedIn, isLoaded } = useAuth();
  const navigation = useNavigation();

  useEffect(() => {
    if (isLoaded && !isSignedIn) {
      navigation.navigate('SignIn');
    }
  }, [isSignedIn, isLoaded]);

  return { isSignedIn, isLoaded };
}

import { useUser } from '@clerk/clerk-expo';

export function ProfileScreen() {
  const { user } = useUser();

  const updateProfile = async () => {
    await user.update({
      firstName: 'John',
      lastName: 'Doe',
    });
  };

  return (
    <View>
      <Text>Welcome, {user.firstName}!</Text>
      <Text>Email: {user.primaryEmailAddress.emailAddress}</Text>
    </View>
  );
}

import { useAuth } from '@clerk/clerk-expo';

export function useAuthenticatedRequest() {
  const { getToken } = useAuth();

  const makeRequest = async (endpoint, data) => {
    const token = await getToken();
    
    const response = await fetch(endpoint, {
      method: 'POST',
      headers: {
        'Authorization': `Bearer ${token}`,
        'Content-Type': 'application/json',
      },
      body: JSON.stringify(data),
    });

    return response.json();
  };

  return { makeRequest };
}

// Update trial count
await user.update({
  unsafeMetadata: {
    trialCount: 3,
    totalIdentifications: 0,
  },
});

// Check trial status
const trialCount = user.unsafeMetadata.trialCount || 0;
const canIdentify = user.publicMetadata.isPremium || trialCount > 0;

// Store subscription status
await user.update({
  publicMetadata: {
    isPremium: true,
    subscriptionId: 'sub_xxx',
  },
});

# .env
EXPO_PUBLIC_CLERK_PUBLISHABLE_KEY=pk_test_xxxxx