I used to get calls from my customer saying that they see insufficient license warnings when login to CUCM.

90 % of the cases reported where due to the OWNER configuration . Remaining 10% are due to other reasons.
With Pandemic many customer started creating Jabber profiles without choosing proper Owner filed which cause the system to consume extra license.

How does Owner filed effect the license usage.
Assume that you supplied 250 Nos 8841 phones with 50 CUWL and 100 enhanced license . Solution was designed assuming that 50 user will be using 3 phones each and remaining 100 users will be using single device.
What happens when you choose owner as Anonymous for all these 250 phones ?
PLM require 250 Device License. Based on the phone model, it can be enhanced, basic, essential. In this scenario we need 250 Enhanced license.
What happens when we choose Owner as User.This cause the system to consider User license.
- If the user has only one device under his name, still the device license will be considered based on the phone model.
- When same user is selected as Owner on two device, Enhanced Plus license will be required.
- When same user is selected as Owner on more than two device, CUWL Plus license will be required.
Assign Owner and Owner-ID
You can assign the Owner and Owner-ID from phone page.

Summary
For Proper license allocation, on Phone page assign required owner filed.