VMware. I used a pirate copy of VMWare about a decade ago, and they detected it was pirated and I was forced to cough up some coins, lest my VMs all became usel

VMware. I used a pirate copy of VMWare about a decade ago, and they detected it was pirated and I was forced to cough up some coins, lest my VMs all became useless, and I had some important VMs which were mission critical to my startup. I have since switched to QEMU though. The migration was painless enough.