Excel - Protection

[Yian]

Dear all,
I have written my own calculation in excel and would like
to send it to others.
The question is instead of lock the excel sheet with
password, is there any other ways to distribute with
protection methods? such as time based (they can used for
30 days, or if they pay the money, they can continue ..
or something like that.
Regards
Yian

 

[jpendegraft]

You can launch an "On_Time" event......to kick off code...

 

[Yian]

do u mean put on_time event under cell change or formload?

 

[jpendegraft]

All depends on how you are wishing to structure it....

If you just want an expiration, just code it under the "this workbook"
object...

If you are looking for a "authorization" to unlock the thing...

create a form that lauches on open and request the user to key in a
password...if it is the wrong one, the clock continues to tick...if it
is the correct one, you unlock the workbook, and kill the form....

 

[Tom Ogilvy]

Any code based protection for a workbook is very weak (the user can always
disable macros).

Any password protection for a workbook is weak (many password cracker
programs available - many free).

All that said, you can write the first use date to the registry (saveSetting
and getsetting methods) and check it on each subsequent use, putting up a
nag dialog.