honour the people that gave lots of money (in my case I payed more than €1000,== when protonmail started.
After a long time I logged in in my protonmail account. Years ago I contributed more than 1000,== because I thought (and still do) that an encrypted service should be available for everyone. So, I supported the development in change for a lifelong membership. It is a bit disappointing to see that I am now a member with a free subscription. Having to pay more if I want to do more. As it happens I don't. Still though. At the time ikt was a lot of money and needed to get through the first stages. Is this the way in which you say 'thank you'? So, my 'idea' is that you honour old agreements.