Let the user set a limit to the number of downloads of a document in the shared folder. Example: allow only one download or allow 5 downloads before the link expires.

Set a post-dated date/time that a link to the shared folder is valid. Example: link is valid >starting< at a time/date set by the user and ending at a time/date set.

Allow user to combine feature #1 and feature #2. Example: A link to a document in the shared folder is valid starting three days from the upload and expired four days thereafter, limited to two downloads total.

A notification sent by email of when a link to a shared document is accessed.