The Media File Renamer is a WordPress plugin that physically renames media files nicely for a cleaner system and for a better SEO. Please read the description as it contains important information.
This is pro version of this free plugin Media File Renamer — WordPress Plugins
The Pro users are given a few more features like manual renaming, renaming depending on the post the media is attached to, logging of SQL queries and a few more options. With the Pro, a good process is to actually let the plugin do the renaming automatically (like in the free version) and to do manual renaming for the files that require fine tuning.
Just overwrite your free version and put any serial in pro tab