%$Lamed
\documentclass{book}

\usepackage[charset = isolat1, spanish, french]{mem}

\scriptproperties{La}{rmfamily = omlgc}
% \usepackage[spanish]{spguill} % <<<<<< Uncomment this line and
%      see what happens !

\begin{document}

Today is «\today» in French.

\begin{spanish}

But it's «\today» in Spanish.

\end{spanish}

\end{document}