Subscriptions for NoMachine software products are per server. This means that you need to install one subscription license on the remote "host" or "server" you wish to connect to. Depending on what subscription you purchase will dictate what features and functionality are made available.

Once the appropriate NoMachine package is installed on the target machine, you can connect to it to access a desktop or application running there. On the device(s) you are connecting from, you can install the free Enterprise Client if you prefer only a connection GUI, the mobile app or any other NoMachine package - they all ship the player component which is what you use to connect. Alternatively, you can make the connection via web-browser if the products supports web-based access.

You may also find the following articles helpful:

Why renewing your NoMachine Server license is important
https://kb.nomachine.com/AR03D00365

Purchasing a software subscription from NoMachine
https://kb.nomachine.com/AR10K00711

Is NoMachine for remote desktop free?
https://kb.nomachine.com/AR03P00972

NoMachine EULA
https://www.nomachine.com/licensing