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I bought Office 2007 long time ago from my university. I have forgotten about the CD, because I use a mewer version in my 3 new computers. A couple weeks ago, I formatted one of my computers and I could not find my new Office disc. I tried to install Office 2007. I got the error message "You have reached the upper limit of installation of this office disc"

How does Microsoft identify a computer? Does each computer have any specific id?

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up vote 3 down vote accepted

The computer's "specific ID" is calculated from the hardware characteristics.

I don't know if this applies specifically to Microsoft Office (I assume it does). From Microsoft's Product Activation FAQ:

How does Microsoft identify the computer's hardware?

Microsoft Product Activation detects the hardware configuration on which the product is being installed and creates hash values for that configuration. A hash is a value mathematically derived from another value - in this case hardware configuration values. Product Activation does not scan the customer's hard drive, detect any personal information, or determine the make, model or manufacturer of the PC or its components. Microsoft uses hash values out of respect for users' privacy. A hash value cannot be backwards calculated to determine the original value. In addition, Microsoft only uses a portion of the original hash values. Together, these hash values become the complete hardware hash that is included in the installation ID.

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Thanks for your answer! The hash values creation is really a good technique. –  user765168 May 19 '12 at 21:37
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