Hello,
Do you want to Enable the Network Threat Protection (NTP) Feature on the client machines OR Install the Network Threat Protection (NTP)?
Enabling the Network Threat Protection (NTP) Feature is enabling the feature via SEPM Policy. Here, enabling the feature requires the Network Threat Protection (NTP) feature to be installed on the SEP clients.
Installing the Network Threat Protection (NTP) Feature means installing the feature via the installation package which requires a reboot upon installation.
Check these Articles:
Disabling the Symantec Endpoint Protection client Network Threat Protection and Intrusion Detection System components
http://www.symantec.com/docs/HOWTO59111
NOTE: The above article is for disabling the Network Threat Protection (NTP). Here the steps remain the same except used for enabling the Network Threat Protection (NTP) feature.
How to add or remove features to existing Symantec Endpoint Protection (SEP) client installations
http://www.symantec.com/docs/TECH90936
Hope that helps!!