They mentioned that they bought premium, so they won’t be seeing ads. Edit: Multiple people below are telling me that purchasing premium does not remove all ads, so that’s actually quite annoying.
As an aside, I really don’t get the logic of using a service like e-mail and just expecting it to be free - it’s very bizarre to me.
If it’s something important to you (as I assume e-mail is), pay for it - or stop whining about ads/nagging pop-ups.
And if you can’t pay for it, download Dovecot and try doing it yourself - it’s a fun experience, and will make you appreciate the work done by email providers. Spoiler alert: it’s a massive pain in the butt.