Complex sentence: The growth began in 2012 and STX Next decided do buy its own building for offices in Poznan, after a year in 2013 company opened an office in Wroclaw, and one year later in 2014 new office in Pila.
Split into simpler sentences: The growth began in 2012 and STX Next decided do buy its own building for offices in Poznan. One year passed and in 2013 the company opened an office in Wroclaw, and another year later in 2014 a new office in Pila.