Limit amount of categories displayed in a post

by

In your functions.php, you can filter the_category_list, which is an array of categories for a post.

function wpse_the_category_list( $categories, $post_id ) {
  return array_slice( $categories, 0, 2, true );
}
add_filter( 'the_category_list', 'wpse_the_category_list', 10, 2 );

And then display the categories in your template file with:

the_category();