Hi,
All licenses include one or three years of free updates (depending the option you choose when purchasing).
Once this period expires, you must renew the
maintenance plan, which actually have a price of 60 Eur by license.
Please note you can renew the maintenance plan at any time, without any extra cost.
Other companies charge you when a major update is released, and previous versions are not always updated to the latest 3DS Max.
We use a different approach, because is not feasible for us to keep updated multiple versions of our plugins. In this way, there is an unique branch, which is continuous updated with latest changes and improvements.
Besides that, updating our plugins for a new 3DS Max version is not a simple process. Usually that implies many changes, specially when there are third party products involved (as render engines).
Thanks for your understanding.