[Feature Request] Pro Site: Email upcoming expire notifications

Hi Kasia,

I love the Pro Sites plugin and I think I have a great feature that could be added to the plugin. It would be very usefull to have a table with upcoming expires. Now I need to remind when somebody expires and manualy renew their account, since I only can accept manual payments.

It would be so great if I could have more knowledge about expires (getting the mails as admin as well, upcoming expire lists, etc).