[HECnet] DECnet on VMS version3

I am trying to get DECnet working on a simulated VAX 780 (with simh) with a 3.x version of VMS. This is largely for nostalgic?reasons. I have the version of VMS 3.0 from John Dundas that Supratim posted nearly a year ago. I have also built a VMS 3.0 system by installing VMS from the VMS 3.0 distribution tape. Both of those systems seem to work?well. However I am failing to find a way of getting DECnet working. I have a DECnet end node key (and a routing key, come to that) from http://iamvirtual.ca/VAX11/VAX-11-software.html but that says that it only works for VMS 3.4 or later. I did try it on 3.0 anyway, but it did not get DECnet to work. It complains?about needing a license. Can anyone help me either upgrade my VMS 3.0 system to VMS 3.4 or higher (or just install the higher version from scratch), or help me find a DECnet key that works with VMS 3.0.