How to detect the current user has an active subscription in woocommerce?

Detect the current user has an active subscription in Woocommerce.

function has_active_subscription( $user_id=null ) {
    // When a $user_id is not specified, get the current user Id
    if( null == $user_id && is_user_logged_in() )
        $user_id = get_current_user_id();
    // User not logged in we return false
    if( $user_id == 0 )
        return false;

    // Get all active subscriptions for a user ID
    $active_subscriptions = get_posts( array(
        'numberposts' => 1, // Only one is enough
        'meta_key'    => '_customer_user',
        'meta_value'  => $user_id,
        'post_type'   => 'shop_subscription', // Subscription post type
        'post_status' => 'wc-active', // Active subscription
        'fields'      => 'ids', // return only IDs (instead of complete post objects)
    ) );

    return sizeof($active_subscriptions) == 0 ? false : true;
}

Or

if( has_active_subscription() ){ // Current user has an active subscription
    // do something … here goes your code

    // Example of displaying something
    echo '<p>I have active subscription</p>';
}

                                                                             Or

if( has_active_subscription(26) ){ // Defined User ID has an active subscription
    // do something … here goes your code

    // Example of displaying something
    echo '<p>User ID "26" have an active subscription</p>';
}