Hi,
There is a whole other license type for using Power BI Embeeded. Now you don´t pay per user as with Power BI PRO, now you pay per render. Every 100 time/month user consumes a report embedded through the azureportal you will be charged with 4.2 Euro.
RLS works great with Power BI Embedded. You will not need a singel PRO License to accomplich this.
Follow this link for more information about pricing:
https://azure.microsoft.com/en-us/pricing/details/power-bi-embedded/