I still run Excel 2007 because as long as it can read and write .xlsx files that my Mathematica models can ingest and output I’m good with that. Every version of Mathematica has a perennial license, even if a new version comes out every year. I want the cloud service? That’s a monthly extra, and I’m cool with that. Office 365, where they randomly decide to shove Copilot down my throat and I lose all ability to edit documents I created if I don’t pay the monthly tithe? No, I’m not cool with that.