What would the process be to update our license from OnPrem to Enterprise?
Once we receive approval to use O365 though, what would the process be to update our license from OnPrem to Enterprise (Hybrid deployment: Kanbo Onprem)?
You start with an installation entirely on premise with your SharePoint 2013 and your KanBo Server (IIS).
Once you get an approval for Office 365 you might migrate all data (Documents + KanBo cards) to an Office 365 + Azure infrastructure and you would then switch the licensing to Subscription or Perpetual.
The easiest way is to choose either Active Subscription or Perpetual and continue this type of licensing after the change to the new infrastructure. Please take into account that migrating will need some additional work that will be billed based on time & material.
The Active Subscription covers the Enterprise License so after we will move your documents to Office 365 (IIS stays where it was before - I've got it now too). We can continue on licensing it like that and it support hybrid. That way everything is simpler.
Regarding the Active Subscription, it is a post pay model so it has no limits on users and after the 3 months a script tells you and us how many users to charge for and then the counter of active users is set to zero. After 3 months the same procedure happens. This allows you to use as many users you need and pay only for those who really use the product and benefit from it.