your commercial v4 licenses are perpetual, and will be always yours.
You can find the latest stable 4.05 versions by visiting your personal Downloads area:https://render.otoy.com/account/download_archive.php
If your licenses are listed as v3 in your OctaneLive page:https://render.otoy.com/account/octanelive.php
You have to upgrade your version 3 licenses to version 4. This upgrade is free and can be done visiting the following link:https://render.otoy.com/shop/upgrade.php
Only if you want to use new versions like 2020.1.3, you have to update your licenses to v2020.