This module depends on Node Comment module and it limits the comments number per node per user for a limited time. For instance, you can set that you want to allow only 3 comments per user for story node type and within 7 days after the node publication date.
You can :
- select on which node types the limit will apply;
- choose if the limit is a global one or a per user limit;
- fix a time limit to add comment.
This module only works for comments, it doesn't work for nodes : for this, see http://www.drupal.org/project/node_limit