Should I work under third party payroll?

I was working at a startup from past one year. They were offering me very low salary. Now I told them I want to resign. They told me we have plans based on your commitments. They said see if you can extend notice period by 2-3 months. Already there is notice period of 2 months. They also said they will not stop me but they will see if there are any vacancies at client side. They are offer is me 5 LPA. But I can’t trust them. I don’t know how much time they will take to tell me if there is any opportunity or not. Or they just want to delay my resignation as there are multiple projects to be delivered in next 3 months. What should I do?