How indicate when a functions was upgraded in relationship to the entire program [closed]

Inline docs are the place to track changes. There are better tools for that: revision control. Use Git, Mercurial or – if you want to stay old-school 😉 – SVN.

Each time you change something, you make a commit: A short note explaining the difference between the last and the new version (example).

Usually, when you look at source code you want to know what it does right now. And why. These docs are important. Everything else, including @since, doesn’t really belong to comments.