There are plenty of programs out there which can end up being required for your workflow - as in, that exact program; no exceptions - and yet, have no Linux or even non-Windows version.
Not everything is a platformm-agnostic subscription-based SAAS yet, nor should that ever be the case.
Sure sounds like labour to me.
And there is no requirement for labour to generate income immediately. A majority of labour is front-loaded, with income being back-loaded.
Server maintenance and updating code to work with current releases is still “labour”. Because sure as shit you’ve been doing these things… no hosting provider is going to let you go 10 years with zero updates or patches to the website or the underlying framework that allows the website to run. Because failing to do that is how entire hosting platforms get rooted and infected with malware.