I needed to reset my computer and thus re-install my Sage 50 Pro. I had the 2018 version and support to end of 2018.
I have the original installation file which installed 2018.1 however it appears my company file was used by a later version - presumably 2018.4. Check for updates says 2018.4 is available but I don't have a current support package and can't update.
My account appears to also have a serial and activation key for Sage 50 Pro 2019 although I have never used it.
So that said I'm looking for a 2018.4 or any 2019 installation file if anyone can help.