It doesn't make sense for the "Subscribers" menu entry to be under Tools.
As stated in http://codex.wordpress.org/Administration_Panels#Tools_-_Managing_your_Blog, Tools is for things such as import/export, backups, upgrades.
The menu for "Subscribers" would fit a lot better under "Users".
This is where my mind intuitively tells me to find the Subscribers menu: right along with Users.
In fact, that's where the other Subscribe2 menu "Your subscriptions" is; so that puts them together.
Right now, Subscribe2 has menu entries under 3 different top-level menus, which makes configuration pages hard to find.