QCAD uses this pricing model. I bought QCAD once over ten years ago. Since then I've bought it a couple more times to get some new feature, but even the origina

QCAD uses this pricing model. I bought QCAD once over ten years ago. Since then I've bought it a couple more times to get some new feature, but even the original binaries I downloaded over a decade ago work fine on my modern linux/windows installs. I'm not sure which operating system is obsoleting all your software on a yearly basis, but it doesn't sound like a very stable computing environment.