請問一下，我媽走咗之後留下層樓俾我，（層樓係長命契，有我媽同我的名）但我層樓現在由我弟弟住在裏面，有人說如果層樓由他人住了一個期限，層樓自然會變成他的，是這樣的嗎？麻煩大家幫我解答一下。?

Thanks! 多謝你的回答。

No.

What you have mentioned is adverse possession (逆權侵佔).

Adverse possession is hostile in nature. To make this simple - the person attempted to adversely possess a property must commit certain illegal acts, such as not paying rents, occupying the property without approval.

In this case, assuming your brother has your approval using the property (rent or not rent), your brother will not consider hostile in this matter and will never be able to adversely possess the property.