The system will automatically use your for the first two cameras you connect.

The "Synology Surveillance Station license free" dream is real only up to 2 cameras. For anything beyond that, you are either buying hardware (second NAS) or paying for software.

You own one NAS. You get two free licenses. If you buy a second cheap, used Synology NAS (e.g., DS120j for $100), you get another two free licenses.

licenses, making them easier to recover if your hardware fails. Billing Variations