How to send email when my plugin is activated?

I’m creating and developing a new plugin for some of my private clients and I do want to see if my clients are sharing my plugin with other people (I asked them not to do that).

How can I do something in my plugin every time plugin is activated, his website sends an email from ‘info@site.com’ to one or more emails I want ‘mygmail@gmail.com’ and ‘myinfo@mywebsite.com’.

By the way, does this include if they update the plugin? Or I just would be able to see who activates only? And does it include the current activated plugin?