How to prevent people from copying my .NET software
I only sell a few licenses of my software and I am worried when I sell them to the same company that they will all just share the CD around the office.  Is there a simple way to keep this from happening?  I don't need it to be hacker proof, and I don't mind if it takes me sending them a license key for each time they buy a new version.  Any ideas?  Nothing too fancy please.  Thanks!
How to prevent people from copying my .NET software
===

I only sell a few licenses of my software and I am worried when I sell them to the same company that they will all just share the CD around the office.  Is there a simple way to keep this from happening?  I don't need it to be hacker proof, and I don't mind if it takes me sending them a license key for each time they buy a new version.  Any ideas?  Nothing too fancy please.  Thanks!