How to transfer pagdi flat rent bill after father’s death?

Our flat is in South Mumbai, and we lived there until 2021. The pagdi flat rent bill is in my father's name. He died recently in 2023. I approached the landlord to transfer the rent bill to my name, but he is asking for money. We are not selling the flat, only transferring the rent bill. I am the sole legal heir (only son). We currently stay in Navi Mumbai due to job reasons. The flat is rented out, and we pay rent to the landlord for two months.