My friend has told me the plot of the movie but he doesn't know the exact name of it.
There's the man who's uncle is a millionaire and he sais that he will give all his belongings to him if he manages to spend 30 million dollars in a month time, if so, after the probationary period, he will be given 300 million dollars. If not, he will be given one million and all the rest will become others'.
Please tell me the name if you know it, I really want to watch that film

Brewster's Millions? Several films have been made from the original novel. I think there may be a more recent version than the one I'm citing here.

Brewsters Millions