Right, I didn't think about that, makes sense :D
You will need to contact one of our sales partners. List of local partners you can find at your local country HPE website.
I'm sorry but I forgot one inconvenient detail... J9420A Premium Mobility Controller End of Sale date was Sept 2016. I don't think you can purchase new contracts for that product anymore. J9421A Access Controller is still an active product, so I'd think contracts for that are still available.
Best thing is to call a local HPE reseller.