Apparently, it comes with 3 licences, it says so on the box (below the feature table).
I've not checked this myself, so it maybe worthwhile going to pcworld (or where ever) to check it out, but I have seen it mentioned on quite a few forums. EG;
click here 2nd bottom
You should also be aware that the Student/Teacher Edition doesn't include outlook (there is a work around so you can use previous vers of outlook, if you need to).
Hope this helps.