SAP Maintenance worker user is not showing in USMM

Hi all,

We have an urgent requirement.

We bought new 6 worker licenses. Now we want to install those 6 licenses to some of the users. But when i checked in "USERTYPES" in USMM, i couldn't find SAP MAINTENANCE WORKER USER. Only the below three are marked and those three are available in system.

Can any one help me how to install worker licenses in our system?

Regards

Praveen