Developers SAP - Registration Key

In Our SAP LAUCHPAD I clicked on Softwate change registration option, next I clicked on Developers then I´m able to see all SAP Users who have a registration key in our company, with this they can develop in our SAP client DEV100.

My question is: How come SAP allow me to record more tan user as a developer in this section If contractually I only bought one licence for one developer?

Thanks

José