Within the software industry, one can recognize a strong trend towards productization, which is the transformation process from customer-specific software to a standard product. Organizations that originally focussed on building custom software regularly reorient towards a market. In order to grow into a mature product software company, an organization has to introduce and adapt its software product management processes. This paper presents a case study on how software product management processes evolve during the stages of productization at a small software company. We identify productization stages at the case company and describe the situational factors and implemented software product management capabilities during those stages. The paper provides a validation of the productization model, and insight into the development of SPM processes in relation to the productization stages.