Adam Saxton gives three methods for using Power BI on your own website:
Developers have the option to use the Power BI REST API’s to embed tiles or reports into their website or application. This option does require that the end user is signed into Power BI. This means that they will need to have signed up for Power BI. They will then see the items that they have access to.
Official Documentation – Power BI REST API’s
I only remembered the first option, but the REST API is very interesting.