@Andres Castillo
What you say above is not entirely true. Esri does have a perpetual model for the on-premises deployment option of ArcGIS Insights. This is deployed with ArcGIS Enterprise.
A perpetual model is not offered for our Insights SaaS deployment option with ArcGIS Online. This is similar to other software and analytic packages. Since SaaS requires cloud storage and hosting, it is not realistic for a perpetual offering.
As far as transferring named users when that user leaves the organization, you have the freedom to do that today in both deployment options.
Does that help and make sense? We really need to get you connected with an Esri Account Manager in the region that you are working within. If you message me, I can help connect you to the right person/people to answer your pricing questions. ssandusky@esri.com
-Scott