Zhè jiāng shì ràng tā zhōngshēn nánwàng de jīnglì.
This will be an unforgettable experience for his whole life.
Tips
usage
终身 vs 终生 (zhōngshēng): They are very similar but 终身 is slightly more common in modern usage and in set phrases like 终身大事 (marriage — life's big event).
usage
终身大事 (zhōngshēn dàshì) = marriage (one's biggest life event). 终身伴侣 = life partner.