I have created a complex spreadsheet with a lot of functionality. I believe
others in my industry might be interested in purchasing this spreadsheet to
use in their operations.

Is there a way to put a license or protect it in some way to prevent those
who purchase it from giving it to others to put on their computer? Perhaps a
window asking for a key and maybe even an expiration date.

I was also thinking of allowing a trial use of the spreadsheet. Can the
ability to open the sheet have an expiration date?

Any help would be greatly appreciated.