Using Windows 7 more than one time

When you get an upgrade of the OS, you can put it on one computer at a time. The same is true for Office. The rule is one key number, one computer (at a time)
Hope this is what you meant, did not fully undersand your question.

Not really sure what you mean so I'll just give a fully detailed response.

Windows 7 licenscing states that one key can be used on only one computer at a time. If you get a new computer, you can format the drive on the old one, then install 7 on the other computer (provided it is a retail, not OEM, copy) without a problem. You can also reinstall 7 on the same computer without issue.

Office 2010 keys can be used on one desktop and one laptop at a time. I'm not sure if MS actually has a way to tell what type of computer it is on, so it may not matter. Point is one key=two computers, unless it is the home and student edition. Then one key = three computers. These keys can also be reused when moving the install to a different computer or reinstalling the software.

With one retail key, you can only use Windows once. If you try to use the key on two different computers, it could end up on MS's "black list". In other words, you will never be able to use it again.

With Office 2010, it depends on the version. With most versions, 2. With home and student, 3. This will explain it a little more: Microsoft's Office 2010 Pricing, Explained | News & Opinion | PCMag.com