Quoted from Chip Pearson's site. Chip is a well-known developer.

All protection mechanisms in Excel are really intended to prevent the user from
accidentally changing a value or some code. The security just isn't strong
enough to provide real protection of proprietary information or information or
code with intellectual property value. For that level of security, you should be
writing your code in Visual Basic 6 or VB.NET. See Creating A COM Add-In for
details about creating a COM Add-In and Automation Add Ins A Function Libraries
for details about creating an Automation Add-Ins.

To follow up on this, here is the location of the page on Chip's site with the
links to "creating a COM add-in"

http://www.cpearson.com/excel/workbooktimebomb.aspx


Gord Dibben MS Excel MVP

On Thu, 14 Feb 2008 14:48:02 -0800, Staanley
wrote:

Hi,
I have an EXCEL file which I use for my own use, but I want to 'loan' to a
few colleagues at work. I want to keep some control over it - my main worry
is that people will copy it, move jobs, take it with them etc., and before
long it will have spread. The program has some commercial value.
Is there any way of requiring a password, say, which is linked to the
computer on which EXCEL is used - in other words, once installed the EXCEL
file could not be transferred on another computer without another password
from me.
Or, any other suggestions would be really appreciated.
Thanks.