There are two possibilities:
Official Streaming: You can watch the original English version on Airtel Xstream Play via Lionsgate Play. Memento Tamil Dubbed
The Narrative Style (The Key to the Film): Memento is famous for its unique storytelling. The movie runs in two timelines: it was a revelation.
Platforms like Amazon Prime Video and Netflix recognized the appetite for high-concept cinema in regional languages. When Memento eventually received high-quality Tamil dubbing treatment, it was a revelation. Memento Tamil Dubbed