The title section of my LaTeX documents usually look like
\\title{Title}
\\author{Me}
%\\date{} %// Today\'s date will appear when this is commented out.
\
If you need to display the version number only in the titlepage, you just need to modify it using
\begin{titlepage}
...
Version 1.x
...
\end{titlepage}
after issuing the command \maketitle.
Otherwise, if you need to recall it in several times throughout the document, it's better to define a variable:
\def\Version#1{\def\version{#1}}
so that you define the version number with \Version{}
and recall it with \version
.