It is very frustrating for a user when entering information to be monitored to find they have reached the limit of items which can be added. They may have to delete one or more entries to be able to add more important items. For example one could add 10 email addresses and still have more to be added when trying to add the eleventh there finally is a warning limit reached. So simple to indicate items remaining or used, e.g. (3 remaining out of 10).
