Howdy,
I'm guessing that you didn't have your virtual MAC addressed pinned to the VM hosting iMC?
Do you have your IMC software registered in your "My Networking" portal?
You will need the Registration ID (I think its called) of the IMC platform software and the new "Virtual Serial Number" that you can get from the "Activate" page below the initial login webpage.
You should be able to recompile a new license-key file from the above 2 pieces of information. I just tried to get into the "My Networking" site to check my methodology and it's "very sorry" that it isn't letting me in :-/
I'll maybe try again in a bit
If you get stuck (i.e. if you don't have registration ID and suchlike to hand) you can throw yourself on the mercy of Support and see if you can get an emergency key sorted out while you try and unravel your paperwork.
I would highly recommend pinning the virtual MAC currently in use to the VM hosting IMC so that it doesn't happen again.
Another good one from the scrap-book of broken dreams:
If you can avoid "DRS-ing" your workload to another host you'll avoid regular unfathomable alert storms. Can happen where the regular IMC node keep-alive / discovery process kicks off and the acknowledgements are delivered back to the host that your hypervisor manager has just auto-migrated IMC off, resulting in a sudden momentary whoopsie on the network where it looks like all the managed nodes disappeared and then came back. Happens in the blink of an eye and very difficult to nail down. Don't let your IMC workload wander free across your VM farm. Anchor it to a fixed host unless the host is dying.
Don't forget the Kudos "thumbs up" button and the "solved" tick to let others know when a post is helpful / useful / amusing.
Thanks
Ian