You need a party host's email addreess.

Ive had a invite but cannot host a party as its closed now.

now what do i do with this keg?

The party-host was closed few weeks ago, because Microsoft needed at least a week to deliver their Windows® Party packs(with a special Signature Edition of Windows 7 Ultimate) to the hosters over the world! I was invited too to host a party on one of themes: PhotoPalooza; Media Mania; Setting Up With Ease; Family Friendly Fun.
The invitation was:
"Be a part of Windows® history.
Host a Windows® 7 Launch Party.
Have Fun. Help Your Friends.
Receive a Signature Edition of Windows® 7 Ultimate.
You host the party. We’ll bring the favours.

Apply online to host a Launch Party. Choose a day from October 22-29 and if you're selected, you'll not only receive a special Signature Edition of Windows® 7 Ultimate but your very own Windows® 7 Party Pack.
Hosting a Windows® 7 Launch Party is easy.

You'll be assisted by House Party, the world's leading party organizer. Pick a theme, then upload photos and videos, chat with other hosts, blog your experience, and download fun favours all from your personal House Party page."

Also IObit Security, and Panda Security are offering free one year subscriptions.
Panda Internet Security 2010 (Offer is only valid to U.S. residents).
IObit Security 360 PRO

So as Kaspersky page says their free one-year license is only for hosters and attendees!