Hello MarykaJohan,
The Product Key on the Certificate of Authenticity (CoA) on the bottom of you laptop is for the Windows Operating System only, which you stated is Win 7 Home Basic on your laptop. This Product Key is only for the installed Windows and should not be expected to activate any version, edition, or Trial of Office.
If you are downloading a Trial of Office, the product key that is shown to you as part of the Trial download process will activate the Trial that you are downloading only. You should not expect this product key to activate any other version or edition of Office. And as with all Trials of Office, it will expire at the end of 60 days or 25 uses (depending upon which Trial and how it was installed on the computer). At expiration, the Trial becomes more or less a file viewer, in that it will open, display, and print any Office documents, but it will not allow you to edit existing documents of create new ones.
In order to continue to use Trials of Office past their expiration dates, you have to purchase a perpetual license for Office in the form of a perpetual Product Key. Please see this Office Help article for more info: http://office.microsoft.com/en-us/help/HA101936151033.aspx
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