If you are looking for the original English film with or without regional support, here are the official ways to watch it:
For Tamil audiences discovering this film for the first time via the dubbed 256 version, the plot is a labyrinthine thrill ride. The story follows , a former insurance investigator suffering from a rare condition—anterograde amnesia. He cannot form new memories. Every few minutes, his slate wipes clean. Memento Tamil Dubbed Movie 256
You're referring to the Tamil dubbed version of the movie "Memento"! If you are looking for the original English