-ms=on : Enables solid archiving for better overall compression.

: Increase this (e.g., to 64MB or higher) if you have enough RAM. A larger dictionary allows the archiver to find more patterns in the data, leading to a "better" (smaller) piece of compressed data.

You can use 7-Zip on any computer, including a computer in a commercial organization. You don't need to register or pay for 7-Zip. Creating Encrypted ZIP files with 7-Zip - DCU