Automatically update WordPress plugins whenever updates are available

auto-update-plugin.php

<?php

function auto_update_specific_plugins ( $update, $item ) {
    // Array of plugin slugs to always auto-update
    $plugins = array ( 
        'bb-ultimate-addon',
    );
    if ( in_array( $item->slug, $plugins ) ) {
        return true; // Always update plugins in this array
    } else {
        return $update; // Else, use the normal API response to decide whether to update or not
    }
}

add_filter( 'auto_update_plugin', 'auto_update_specific_plugins', 10, 2 );