I don't think OP knows much about computers.
1. RAM is Random Access Memory. AKA Microchips on the green circuit (mother) board. There are no microchips on a DVD disk.
2. Once you close a DVD or CD, after writing files on it, you can close the disk so no more files can be written on the disk, but the files can still be copied easily by anyone who has the disk.
I think what you mean to say, is how can you copy files to a DVD and then prevent somebody else from copying the files for themselves. It is not possible. Believe the music industry would love to and have tried to stop the illegal copying. They can't do it either. Sony spend $100 Million dollars inventing copyright protection software and it was hacked in minutes by a simple magic marker.
If you are giving the disk to a really naive person, you can install a boot menu on the DVD, so when it is put in the machine, it automatically loads a menu making it difficult to read the files for copying. It works for for the 90%. But that sounds beyond your displayed technical comfort level.
If you don't know what a DVD-RAM disc is, don't contribute. It's an older disc style which was often confused with magneto-optical media, but looks distinct from "normal" DVDs, because of the "pits" on the rewritable surface which are the blocks used for addressing. DVD-RAM is always rewritable, but a DAO or TAO disc can be "closed" like any other DVD making it more compatible with Windows.
At least someone who knows what I'm talking about.
I don't want protect copyright. I just need DVD RAM to archive some documents and the SOP says to use read only DVDs.
In my program I can choose finalize. Is it the same as close?
If you write to disc using a single-session mode, it will finalize automatically. If you use it as a rewrite medium, adding files periodically, you will need to finalize/close later.
Noob, what r6 said.
Additionally, a "closed" DVD-RAM disc will never be a DVD-ROM, or read-only DVD-R, they're totally different from other DVDs, some are even double-sided and come in plastic cartridges, think floppy disk. If your laptop can't read/write DVD-RAM, it won't work. On the other hand, most DVD writers these days can handle DVD-RAM.