Limit Use & Sharing

I've spent a fair amount of time creating a financial planning spreadsheet that I'd like to try to sell. My biggest problem is selling it to people and allowing them to use it without them being able to email it to anyone else. My first thought was to code it where a macro will run when the spreadsheet opens that checks if the spreadsheet is being opened on a specific computer and will close down if it is opened on an unauthorized computer. I'm not sure if this will work or how to code it