Land Restriction of Use

[Mak K.]

Hi, I am looking at some lots in Harris county/TX area and I see many of them have "Restriction of Use" document during the listing. The restrictions are " The house needs to be 2500 SF or 3000 SF living space, and other restrictions similar to the HOA. Some states the lot cannot be divided or can only be divided in 2-3 smaller lots etc etc.

Are these restrictions which stay with the land for its entire life? Or can this be changed down the line?  Why would the seller make such restrictions and is there a way to change it?