In the workbook open event, check the date against a date you have written
on a worksheet in the addin.

If the date is exceeded, check another cell for an appropriate passcode, if
found, continue to run the workbook_open event, otherwise put up a prompt
for the pass code - if valid, write it to the cell and continue to open else
put up a nag dialog, then close the workbook.

--
Regards,
Tom Ogilvy

Juan wrote in message
...
I downloaded an AddIn from a website, this AddIn had an
expiration date after which you had to pay the programer
for a pass code. I payd and it worked. I want to learn how
to do this. Can someone help pls.

Regards. Juan