There is no early access license for IntelliJ IDEA available on
intellij.net now, so you can use MPS only for 30 days (untill evaluation
license expired). But we need you feedback for MPS, so if you send us
short description of things which you want to do with MPS we will send
you personal license that will work until new EAP build will be available.
You can contact me at Konstantin.Solomatov at jetbrains.com