Would be MOD that limits user time within a group.

So when we give access to download for any members through the "SMF Downloads Directory"
He will have access for a specified time while you are in that group.

Example:
I want to put a few members in a group that will have access in some plates and downloads from the forum for a week. Then they will be automatically removed from the group.

The early time would begin counting as soon as the Member was added in that group.

Sorry, but that sounds quite specific for your forum, I don't think I'll be doing that for the public release.