PHP code inserted in label texts (even directly in the database) is never executed as this would pose some serious security threats.
A quick hack...
Copy the files of the courseformat you are using (in
course/format) and create your own course format.
Add the code you would like to be included in
I guess the bottom of section 0 could be a good place to display this kind of information. To do this look up
echo '</td>'; echo '<td class="right side"> </td>'; echo '</tr>'; echo '<tr class="section separator"><td colspan="3" class="spacer"></td></tr>';
and add your php code above these lines.