Microsoft has an ongoing launch offer / upgrade offer for existing users of Windows 7 to upgrade to Windows 8 for INR 2,000 (~USD $50). This can be availed via the Windows 8 Upgrade Advisor app.
Here's my question- If I opt to purchase the upgrade, do I also need to install it immediately or will I be given a product key that I can use at a later time? I believe this upgrade offer is time-bound and will be valid up to some time in JAN 2013.