When you use LonMaker you can only commission/decommission devices even if you have a LNS Application that can commission/decommission devices. Device credits are only needed for commissioning/decommisioning.
1. If you are using only LonMaker as your network tool then you don't need to activate the LNS Server.
2. If you are also using LNS Apps (third party LNS Apps or LNS DDE Server), you may need to activate the LNS License with the LNS License Wizard (which is different then the LonMaker License Wizard) in order for your LNS App to run.
Note: When you start LonMaker it starts the LNS Server which allows you to run LonMaker and the LNS app without activating the LNS Server. But if you intend to use the LNS App without LonMaker already running then you need to activate the LNS Server.
Use the LNS License Wizard to activate the LNS Server (you only need 1 device credit).