Alma 37:1 - 37:5
Alma 37: 1 And now, my son Helaman, I command you that ye take the records which have been entrusted with me;
Alma now passes responsibility for the maintenance and safety of all the records that were given to him by his father Alma Sr. to Helaman.
Alma 37: 2 And I also command you that ye keep a record of this people, according as I have done, upon the plates of Nephi, and keep all these things sacred which I have kept, even as I have kept them; for it is for a wise purpose that they are kept.
Alma also commands his son to continue keeping a record of the people as he has done up to this point in the history of the Nephites. He is to record the sacred events among the people as it is a commandment by the Lord and there is a good reason for doing so.
Alma 37: 3 And these plates of brass, which contain these engravings, which have the records of the holy scriptures upon them, which have the genealogy of our forefathers, even from the beginning—
One of the reasons is that they contain the holy scriptures and a genealogy of their ancestors.
This would include the Brass Plates. It looks like the genealogy of the Nephites may have been kept as well.
Alma 37: 4 Behold, it has been prophesied by our fathers, that they should be kept and handed down from one generation to another, and be kept and preserved by the hand of the Lord until they should go forth unto every nation, kindred, tongue, and people, that they shall know of the mysteries contained thereon.
Another very significant reason is that these records at some future date will be published and circulated throughout the world so that all people on the earth will know about the Nephites and their history and the prophecies that is in the book.
Here is one of the prophecies that this book makes that has come to pass. The Book of Mormon is in over a 100 languages and has long passed over a hundred million copies printed. Considering that this statement was in the Book of Mormon when first printed in 1829 this is fulfillment of prophecy. This alone, should give testimony to the legitimacy of Joseph Smith being a prophet. No one would say that a book he produced would be known to all the world. That is a very bold thing to say but since Joseph Smith was a prophet, he could say it and it would and is coming to pass.
Alma 37: 5 And now behold, if they are kept they must retain their brightness; yea, and they will retain their brightness; yea, and also shall all the plates which do contain that which is holy writ.
So if Helaman will keep the records up to date they will stay as bright and shiny as they are now as Alma passes them on to Helaman. This will include any all records in his keeping.