您可以使用user_register 用户注册时运行用户元更新的操作。

/**
 * Sets the user meta key \'_sb_pkg_type\' to \'free\' when a user registers.
 *
 * @param int $user_id ID for the user who has registered.
 */
function wpse_update_user_meta_pkg_type( $user_id ) {
    update_user_meta( $user_id, \'_sb_pkg_type\', \'free\' );
}
// Fire late to try to ensure this is done after any other function hooked to `user_register`.
add_action( \'user_register\',\'wpse_update_user_meta_pkg_type\', PHP_INT_MAX, 1 );

我确实验证了此代码是否更新了用户元密钥_sb_pkg_type 值为free 当新用户注册时。