The development milestones of Windows 7 are time-bombed, as is the case with all Microsoft pre-release software. When it comes down to the Milestone 3 releases of the next iteration of the Windows client, the expiration date is officially set to August 1, 2009. This despite the operating system indicating via Winver that it will expire as early as July 1, 2009. With or without a product key, pre-release versions of Windows 7 including Build 6801 and 6956, but not earlier than 6801, can be used up until August 1, 2009.
The expiration date of Windows 7 is delivered under the Time Sensitive Software section of the End User License Agreement. “This software will stop running on August 1, 2009. You may not receive any other notice. You may not be able to access data used with the software when it stops running,” Microsoft informs.