Is there a way for the developer of an App Store application to tie a sale to an individual user/device ID/Apple account? In other words, a method for the developer to double-check that a specific user has legally purchased the software?

I haven't been able to find a reliable answer to this yet. I'm not looking for specific code examples, just some sort of idea as to how possible (or difficult) this is.

My intent isn't to penalize piracy; it's to be able to provide additional benefits to paid customers. As such, I'm not looking for a way to identify a cracked or pirated version, which I gather has already been solved.

Thanks in advance for any help you can provide!