Free Article Limit for Visitors (Metered Paywall)

// Free posts per visitor every 30 days.
$wpide_free_articles = 3;

$wpide_meter_read = array();

add_action( 'template_redirect', function () use ( $wpide_free_articles, &$wpide_meter_read ) {
    if ( is_user_logged_in() || ! is_singular( 'post' ) ) {
        return;
    }

    $read = isset( $_COOKIE['wpide_meter'] ) ? array_map( 'absint', explode( '.', sanitize_text_field( wp_unslash( $_COOKIE['wpide_meter'] ) ) ) ) : array();
    $read = array_values( array_filter( array_unique( $read ) ) );
    $id   = get_queried_object_id();

    if ( ! in_array( $id, $read, true ) && count( $read ) < $wpide_free_articles ) {
        $read[] = $id;
        setcookie( 'wpide_meter', implode( '.', $read ), array(
            'expires'  => time() + 30 * DAY_IN_SECONDS,
            'path'     => COOKIEPATH ? COOKIEPATH : '/',
            'domain'   => COOKIE_DOMAIN,
            'secure'   => is_ssl(),
            'httponly' => true,
            'samesite' => 'Lax',
        ) );
    }

    $wpide_meter_read = $read;
    nocache_headers();
} );

add_filter( 'the_content', function ( $content ) use ( $wpide_free_articles, &$wpide_meter_read ) {
    if ( is_user_logged_in() || ! is_singular( 'post' ) || ! in_the_loop() || ! is_main_query() ) {
        return $content;
    }

    $id = get_the_ID();

    if ( in_array( $id, $wpide_meter_read, true ) ) {
        $left = $wpide_free_articles - count( $wpide_meter_read );

        return '<p class="wpide-meter-note"><small>' . esc_html( sprintf( _n( '%d free article left this month.', '%d free articles left this month.', $left ), $left ) ) . '</small></p>' . $content;
    }

    $html = '<p>' . esc_html( wp_trim_words( wp_strip_all_tags( strip_shortcodes( get_post_field( 'post_content', $id ) ) ), 40 ) ) . '</p>'
        . '<div class="wpide-meter-wall"><p><strong>You have read your free articles for this month.</strong></p><p><a href="' . esc_url( wp_login_url( get_permalink() ) ) . '">Log in</a>';

    if ( get_option( 'users_can_register' ) ) {
        $html .= ' or <a href="' . esc_url( wp_registration_url() ) . '">sign up for free</a>';
    }

    return $html . ' to keep reading.</p></div>';
}, 1 );