Add More Fields to Users Pages (Admin Panel)

You can hook manage_users_columns to add (and I suppose remove) columns from the All users display. This tutorial details that.

You might be able to hook user_edit_form_tag to do the trial vs not trial at the top…but I’m not sure, you’d have to tinker with it. I think you’ll probably end up having to use something else (WP_Error might be a good way to go), but that would be where I started.