I use some specialized engineering software that's by subscription. The subscription pays for the ability to use the latest version, otherwise you're locked out

I use some specialized engineering software that's by subscription. The subscription pays for the ability to use the latest version, otherwise you're locked out. And it pays for support. Only the latest version is supported. Even if you're paid up, if you have an issue, the first thing they ask you is if you've installed the latest version. Mechanisms vary. The license I'm using can either be managed through a networked license server or a physical dongle. Don't forget to set aside some resources just to maintain and support the licensing and purchasing processes.