Without a licence you can have one translation set and translate between two languages, such as from English to French, but you cannot add other languages.
On your local machine, where the domain ends in either .localhost or .local, you can have as many languages or translation sets as you want. However, when you move to a production server, the licence limits will apply.
Purchase a Licence
Go to the website https://jumoo.co.uk/translate/purchase
Add Licence Key to the Site
You will find the licence key in Settings -> Translation Manager -> licence.
The licence is stored in a file (config/translations.licence.config) that can be copied between servers.