Go to your dashboard settings page of the project. Click the upgrade premium modules button.
When you add premium modules to your project the hosting cost will be 15€/month instead of 10€/month. It doesn't matter if you add one or all premium modules. More premium modules will be released later this year.
Select the language manager and click install.
Login to your project. Go to language management and add all the languages you want to add to your website.
More information about language management: http://knowledge.sitemanager.io/sitemanager-cms/language-management/add-languages-to-your-project