While purchased licenses can be migrated between Synology servers, the free default licenses are bound to the hardware and cannot be transferred to a different NAS unit.
You will find forums offering "license generators" or cracked .lic files. These are often malware designed to encrypt your NAS (ransomware). Furthermore, Synology can detect invalid licenses during firmware updates, resulting in a bricked Surveillance Station or voided warranty. synology surveillance station license free