And how many times you have to update your app? How many time you need for maintain?

I’ve been maintaining Ember apps since 2015 and there’ve been 4 new major versions I’ve worked through, but the project’s deprecation policy and migration tooling have enabled incremental migration over time so there’s never been a need to hard fork / rewrite the app in a way that has occurred with several other (once-)popular web frameworks.

Yes, the update politics of ember is a good example for all. But it comes normally with a cost (features, speed, better solutions, whatever.... don't know currently enough about ember to form a judgment there).

I used ember too for a little own project, when it was version 1 (ONE), but i can't remember today why i not used it anymore.

Respectfully Ember is not current at all. Might as well call BackboneJS or Marionette current as well.

Ember still has significant updates, it's still innovating alongside the best of them, it still has annual conferences, and the productivity a team gets by choosing Ember is still right alongside most popular frameworks for creating and maintain ambitious web applications. The same cannot be said for Backbone or Marionette.