What specific appears when you try to start the service manually?
Troubleshooting: NiceLabel Proxy Service 2017 Is Not Running nicelabel proxy service 2017 is not running
If the service starts but stops immediately, it's often a permission issue. The service account may not have the rights to run. By default, it might be set to a specific user account that has issues. What specific appears when you try to start
In configurations using SQL Server Express (installed by default with NiceLabel), the Proxy Service depends on the database being available. nicelabel proxy service 2017 is not running