Hello at Enpass Team,
I perfectly understand the fact that you need some income for the recurrent cost. And that the Pro/Premium users with lifetime licence don't give you any more revenue. But what you did with the "new Premium features but none to Pro users" poses a problem because as many told before me, none will trust you anymore. What next ? Deluxe Premium ? Platinum Premium ? At first, the lifetime licence can seem like a great way to begin your company or to promote your service/software but on the long way, it'll become a nightmare, financially speaking. However, once you offer such option, it's really hard to back up.
I have no idea how much Pro/Premium users with a lifetime licence you have compared to Premium users with subscriptions. But if the number is low then that shouldn't be a big financial problem. All Pro users have a lifetime licence not by choice but because there is none other options (except the free option) before and they are the same people who promoted Enpass at their family, friends and coworkers. Doing anything that will do to you to lose your promoters is not a good idea.
Remember, Bitwarden cost only 10$/year for get Premium features for all users (old and new). If you don't want lose more user/customer, it'll be best that you found a mean to correct your ways of doing things. What you just did is really risky. Asking for a optional donation to lifetime users, would to be better option because any satisfied lifetime user would not have a big problem to help you if the need is there.
It's all what I wanted said.