My 5 months old keep on sucking his thumb when he is hungry or to smooth himself to sleep. I am worried if this become a hard ot quit habit. Will it go away when he is older?

It is difficult to prevent him from sucking his thumb/fingers. Many ppl ask me to stop my boy from putting it into his mouth but i cant stop him.. so i let him be. I offered him a teether when he is awake to play with. By 5 months old, i'm already offering him a bolster/bean bag to hug it to sleep. Slowly, he no longers need to suck his thumb to sleep. He will hug his bolster and fiddle with a part of it till he fell asleep while I pat him. Now, he smells it instead to make himself slp while I still pat him. It makes him feels calm and he sleeps like tiz till now.