Maybe I will live an apartment because I have a friend who is living there, so I can get a discount of renting a room. It sounds good, but I would say this to make it better: "I might live or stay at an apartment, since my friend is staying or living there as well. So, therefore I am eligible to get a discount on my rent."

I will probably live in an apartment because I have a friend who's living in there. Therefore, I could get a discount by renting just a room.

May be I will stay with a friend who is living in an apartment to cut the cost of renting a room myself.

Maybe I'm going to live in an apartment (or a flat) where a friend of mine is living, so that I can share my rent expenses with him.

I might live in an apartment with my friend because i would be able to get a discount on my rent living with him/her.