Hi Roberto,
what do you mean by "archive key" ? Alfresco can store the document and metadata, relating to that document. If you mean a key as beeing information, stored in some field (aka property), yes you can do it. If you want to automatically update the alfresco property, you need to store the informaton a word document property and adjust the alfresco parser to read out the information. Search the wiki about "extract metadata"
Norgan