When using Raytec's MIP integration plugin to add illuminators to the system (https://www.rayteccctv.com/blog/2021/06/how-to-integrate-with-milestones-xprotect-video-management-system/), do we have to purchase device licences for our Xprotect installaion?

Milestone’s licensing is based on devices added to Recording Servers and we don’t charge for using MIP SDK plugins. Since it looks like Raytec units are not added to Recording Servers like cameras, then there is no additional licensing from Milestone.