\documentclass{article}

\usepackage{hereapplies}

\begin{document}

\title{Some title}

\author{Some author}

\maketitle

This is concept one. To find this concept applied, please
see \whereapplies{conceptOne}.

This is concept two. To find this concept applied, please
see \whereapplies{conceptTwo}.\newpage

\hereapplies{conceptOne} This is page \thepage. As you can see,
``concept one'' applies here.\newpage

\hereapplies{conceptTwo} This is page \thepage. As you can see,
``concept two'' applies here.\newpage

\hereapplies{conceptOne, conceptTwo} This is page \thepage. As you
can see, both ``concept one'' and ``concept two'' apply here.\newpage

\hereapplies{conceptTwo} This is page \thepage. As you can see,
``concept two'' applies here.\newpage

\hereapplies[myref]{conceptOne} This is page \thepage. As you can
see, ``concept one'' applies here. This point in the document is
labeled \texttt{myref}.

\end{document}