slic/netid_servers is a SAP Parameter attribute which is used to control Network ID servers for flexible license mechanism information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
This parameter can be used to activate the flexible license mechanism.
The message server then does not use its local hardware ID anymore. It
uses the network ID of one of the specified ID servers instead
(SAPHostControl). This makes it possible to move the message server to
another hardware without losing license(s). One more more ID servers can
be specified, separated by spaces. Every ID server must be specified as
follows: <(><<)>hostname>:<(><<)>port>. The port is normally the
IANA-registered default port 1128 of the SAPHostControl. If the value is
empty, the message server uses it local hardware ID.
Example
"idhost1:1128 idhost2:1128"
See SAP Parameter Documentation for full SAP documentation for this profile parameter.