Tony,

There is no foolproof way to do this. Passwords are easily broken, the
Registry can be modified, and on and on. You might have a look at the
procedures described on "Time bombing A Workbook" at
www.cpearson.com/Excel/WorkbookTimeBomb.aspx. This page doesn't get into the
topic of activating a workbook with a license key, but it might give you a
"big picture" view as to what sort of code is involved.


--
Cordially,
Chip Pearson
Microsoft MVP - Excel
Pearson Software Consulting
www.cpearson.com
(email on the web site)

"Tony Starr" wrote in message
...
I am developing an Add-In that I wish to sell at some stage. Does anyone
know how I can go about creating a demo version that will expire in 30 days
unless a licence key is entered?

Any help would be greatly appreciated.

Regards
Tony