We were able to grab the product key too as advised here : http://community.powerbi.com/t5/Service/Power-BI-Report-Server-product-key-for-on-prem-only/m-p/2783...
.One question though. Could this product key be used just once ? We have a Development, Acceptance and Production environment. Wondering if the product key is applicable to multiple environments. If not, how do we go about it insalling in the three environments?
Based on my test, it's able to use the Power BI report server license key in different environment.