The licence renewal is the bill you can see. The real cost of a proprietary desktop is the pile of smaller ones stacked behind it — per-seat client access licences, the antivirus subscription, the backup add-on, and the upgrade you’re forced into the moment support ends.
In this piece we add up what a typical ten-person office actually spends per year before anyone has done a single day of work, and where a Linux migration quietly removes each line.