Workbook protected after some date dd/mm/yyyy

[Rodrigo Ferreira]

How can I prevent user to use my workbook after some date?
eg. until 10/12/2006 the workbook works fine, after this date, the user
cannot open the workbook

 

[Otto Moehrbach]

There are various ways of doing what you want, none of which are very
secure. All such systems can be easily broken by anyone with knowledge of
Excel.
One way is to have a Workbook_Open macro that checks the current date.
When the critical date is reached, the code within that macro can
erase/delete the pertinent data within the file, then save the file. Post
back if this fits what you need. Provide details about what you want
erased/deleted. HTH Otto

 

[Rodrigo Ferreira]

Thanks Otto,
I know that is easy to break this macro but I want to raise difficulties.
This way that you wrote is good but if the user change the date of computer,
he can use the workbook again.

Any idea?

 

[Rodrigo Ferreira]

In other question, I would like to retrieve a date from a site that have a
atomic clock to make somthing like that.
When open the workbook, it check the date on internet and if date >
10/12/2006, the workbook dont open for user.
But I dont know any site that have this date...

 

[Otto Moehrbach]

Well, you see the problem. One way would be to write the code to count the
number of times the file has been opened and limit that number. The number
of openings would be stored in a VeryHidden sheet (that way the sheet will
not show up as being hidden if he does Format - Sheet - Unhide). But that
would limit the user opening the file a number of times in one day. What
ideas have you come up with? HTH Otto

 

[Otto Moehrbach]

That's way beyond my knowledge. Sorry. Otto

In other question, I would like to retrieve a date from a site that have a
atomic clock to make somthing like that.
When open the workbook, it check the date on internet and if date >
10/12/2006, the workbook dont open for user.
But I dont know any site that have this date...