Anti Virus does not work after reinstalling Mac with the same version as before
Been happily using F-Secure Anti Virus for Mac, and still have half a year paid license time ahead of me.
Now I reinstalled my Mac with Mavericks 10.9.5, same I had before, and ran into issues getting F-Secure to work.
At first, tried to download F-Secure from the website. Download worked, but the installer refused to do anything as it wanted Mac OS X 10.11 or higher to even install.
So I installed the same version of F-Secure I had before. Not easy to find the installer, because F-Secure provides only the current version, nothing that works with older systems. But I got one and it installed without issues. Also starts and runs without problems, and asks for a license key.
But the license key doesn't work. Don't get me wrong, the key works, it's straight from the user account on the F-Secure website, valid and not used elsewhere. But when entering the key, there is an error which says: Unknown error "null" - please contact support.
The interesting part is, this same version and this same key have worked fine on this exact same version of Mac OS X, just a day ago. Made a clean reinstall, and it gives me an unknown error.
Does F-Secure try to get rid of a customer?
Please don't even suggest updating the operating system. I am simply not ready to pay for all the other licensed software that I have up and running without problems on Mavericks, which will no longer work when I get something new.
So how is it possible that the software works as it used to, but somehow no longer has the capability to verify the key I gave it?