Unstick Sticky Posts Automatically After a Few Days

// Days a post stays sticky.
$wpide_sticky_days = 7;

add_action( 'init', function () {
    if ( ! wp_next_scheduled( 'wpide_unstick_old_posts' ) ) {
        wp_schedule_event( time() + HOUR_IN_SECONDS, 'daily', 'wpide_unstick_old_posts' );
    }
} );

// Remember when each post became sticky.
add_action( 'post_stuck', function ( $post_id ) {
    $since             = (array) get_option( 'wpide_sticky_since', array() );
    $since[ $post_id ] = time();
    update_option( 'wpide_sticky_since', $since, false );
} );

add_action( 'wpide_unstick_old_posts', function () use ( $wpide_sticky_days ) {
    $since   = (array) get_option( 'wpide_sticky_since', array() );
    $sticky  = array_map( 'intval', (array) get_option( 'sticky_posts', array() ) );
    $changed = false;

    foreach ( $sticky as $post_id ) {
        if ( ! isset( $since[ $post_id ] ) ) {
            $since[ $post_id ] = time();
            $changed           = true;
        } elseif ( $since[ $post_id ] < time() - $wpide_sticky_days * DAY_IN_SECONDS ) {
            unstick_post( $post_id );
            unset( $since[ $post_id ] );
            $changed = true;
        }
    }

    // Forget posts that were unstuck by hand.
    foreach ( array_keys( $since ) as $post_id ) {
        if ( ! in_array( (int) $post_id, $sticky, true ) ) {
            unset( $since[ $post_id ] );
            $changed = true;
        }
    }

    if ( $changed ) {
        update_option( 'wpide_sticky_since', $since, false );
    }
} );