Windows 7 beta download availability is extended up to Feb 10th by Microsoft. If you wanted to test Windows 7 beta but not yet downloaded, you have the time until Feb 10th after that it will be removed from public download. For those who have started the download but couldn’t finish can download until Feb 12th.
After Feb 12th you may not be able to download Windows 7 beta from Microsoft, but you may get it from the torrent sites. Product keys for the Windows 7 beta will continue to be available even after Feb 12th according to Windows team blog. And the above mentioned dates do not apply to MSDN and TechNet subscribers, the Windows 7 beta downloads are available for them through out the beta period.
Windows 7 beta version will expire on August 1st.