Original is
"I always thought about you after we finish our conversation."
The translation is
"Увек сам мислио о теби након што завршимо наш разговор."
Hey Kozo-san, you can count on me every time you need something to be clarified.
Поздрав !
Thank you for your kind reply. I deeply appriciate you. And I'll kerp studying Serbian language. Хвала пуно.
Dear Kozo!
Two action finished in the past, one after the other should be put into "pluskvamperfekt".
So: Увек сам мислио о Теби након што бисмо завршили наш разговор.
(The Imperfect from biti/бити and participle from završiti/завршити.