With Passthrough Print LMP key active, you will see this messages in the TPX startup:
TPX9925 OPTION PPS OF UNICENTER CA-TPX IS AUTHORIZED
When you remove the LMP keys, these will disappear after the next IPL.
To see if you have Passthrough print tables set up, check TPXADMIN: -select option 2, TPX System Options. -select option 5, User Passthrough Print Management.