Hi!
I need to take netflow only for users who have limit tariffs. All users a take Authorization from radius. Is the way dynamical take netflow only from PPPoE interfaces of "limit tariffs users"?

P.S.
Is the CoA still don't work for PPPoE? Why is the radclient from freeradius-2.x don't support by mikrotik??? (with invalid signature (err=2)! (Shared secret is incorrect.)) I have try it on 4.11 and on 5.0beta6.

Is the CoA still don't work for PPPoE?

yes
that's why i use MPD - it's more powerfull in PPPoE/PPPTP aggregation than MT, but if MT support's MPD fetures i'll convert all my MPD PPPoE BRAS-es to MT PPPoE BRAS-es