Which License
How you activate your licence depends on your Deployment Type.
Turnkey
Turnkey servers ship with a licence key already on the device. Enter it at first boot and you're done.
Self-Install
Buy your licence before installation, or install the Sensa image on a 14-day trial and enter your key later. Once purchased, run the Reconfigure option to add the key.
DIY
Add the Sensa app to your Home Assistant, then enter your licence key in the app settings. The same 14-day trial is available before purchase.