Protecting content - restricting copying of pdf by users

[AD1]

Hi - I'm using NitroPro10, and I produce training course handouts that are content-rich for classroom-based courses. I've provided paper copies for the handout to delegates up to now.

I'm starting to run training courses virtually, and need to email the handouts as pdfs to the individual delegates.

How do I stop the recipients from copying the handouts to their friends, so others get the material for free? I have used a time-expiry Java scruipt that I found in the past, but that doean't seem to work when the pdf is opened in MS Edge. Is there a time-expiry script that will work in all pdf readers? Or a way of setting a permission that the pdf can be opened by one user, but only one user? Or any other ideas?

Thanks, 

Andrew D