Check out Chip Pearson's TimeBombing method.

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

Note also the URL to "forcing users to enable macros"


Gord Dibben MS Excel MVP

On Mon, 20 Oct 2008 08:12:00 -0700, Teddy-B
wrote:

Good Point - Does anyone think that this idea is a good foundation for a
stronger plan or idea?

"Mike H" wrote:

Hi,

This falls over as soon as a user doesn't enable macros and I don't think
you would need to be 'good' to defeat it, anyone with a little knowledhe and
Google would be able to to do it.

Have a look here

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

Mike

"Teddy-B" wrote:

I've seen a couple of questions regarding password and/or macro expiration in
the community and I had an idea! Please respond to tell me what you think or
to expand the following:
Excel does not provide expirations for macros or password (I have my
passwords all set to protect/unprotect with macros) - However: It may be a
clever idea to write into the macro a certain cell reference that must match
a code that the writer puts into said cell.
For example I could write a mcaro that will work fine in this month's
workbook because the today() hidden in a special cell matches the current
month - When the month turns - the macro becomes useless because the info in
the special cell on the workbook no longer matches the burrent month/year.
RESULT = a sort of hidden expiration written into the macro itself.
Granted, a good workbook writer could figure this out, but not just
anybody! Most peole I know don't mess with macros.
Can anyone think of a better way - maybe expound on this or toss in a
twist?

I'LL be lQQking for your replies!