If you are writing the software yourself, it would be a simple addition
to make a registry key with the encrypted date the program was first
run.  It would be fairly easy to break unless you had a custom installer
that created the key and inserted it in the registry.

I've seen other software do something a little different - You have to
register whether you pay or not.  If you register for a demo or free
license, then the key given has the "do not work after" date embedded in it.

A simple script on a web page would hand out the keys along with a link
to the download.

Another thought is you can automate the packaging of the software when
you distribute it.  If it's zipped, for instance, you simple execute a
command on the web server to add a file to the zip, then provide a link
to that file, which is destroyed later that day.  The file you insert
has an encrypted date in it.

There are all sorts of ways of doing this.  Of course, we'd have a
better chance of hitting the nail on the head if you told us how much
you are selling the software for, the market you're going after, and how
you plan on distributing it.

If you're selling it to hackers, for instance, you can do just about
anything you want and it'll still be cracked the day afte you release
it.  If you're selling to large corporations you can probably employ a
fairly simple scheme.  If it's work only $15/copy then you can probably
go with a simple scheme.  $1500/copy and you should be thinking about
hardware keys.  If it's distributing on the internet then you have some
more options with regards to keys and how the program gets permission to
run (ie, you retain a little more control).

-Adam

D Lloyd wrote:

>Hi,
>
>Anyone have any knowledge of a simple way of time limiting software or a
>freeware/inexpensive app that encapsulates your app to do the same job?
>
>I have some thoughts about how it could be done by myself but they are
>scuppered when things begin to reach the level of what to do if the
>installer does not have admin rights etc etc. I have had a quick snift
>around the net for such information but have not really found a great deal.
>I also have a Sentinel software dev pack to look into......
>
>Any ideas?
>
>Best regards,
>Dan Lloyd
>
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