Personal trainers, or no?

Meganisaface

I currently have one for 4 jump start sessions. I've never had a trainer before so I'm wondering if anyone knowledgeable could help to understand their position in my life and is it worth it? What questions should I be asking? is 30 min. sessions the norm? He's pushing me to continue sessions with him even if it is only once a month(which is still a pretty penny to me) I'm not sure if it's worth it or not. He seems to help me but I feel like I should already have a workout plan. What if I can do this on my own? Insight is much much appreciated!