Thanks for your help, much appreciated and clears things up.
I'm aware of the 2 options when renewing / adding licence, from having a test MR33 - i'll be sure to select 'update'.
We are waiting on a quote from Cisco for renewal.
I appreciate that the MX60 isin't a rocket by today's standards (mainly 100Mbps WAN), but it'll do for another year.
I'm curious as regards to end-of-life. When the MX60 reaches EOL, what happens it? When the licence expires, does it just die or what? Seems like a bit of a con to me.... after buying the hardware / licence for X years, does the device just become redundant?