Linux

Steam probably.

Although I don't use them, the Jetbrains products should be near the top of the list.

DaVinci Resolve is THE video editor on Linux. Unfortunately the libre apps for it don't get even close, to the point that even with all the limitations in the free and paid versions, it still is the best option.

Also shout out to Bitwig Studio, although I don't use it.

Steam

vibeogames

Reaper. Great usability and decent Linux support out of the box (looking at you, davinci resolve). Generous free trial and a cheap one-time payment for a license. LMMS has served me well and is fine for basic stuff, but reaper is a whole other level, both in features and usability. I've heard good things about ardour too but have yet to give it a try.

Half-life: Alyx, Baldur's Gate 3, Elden Ring, ... you get the idea. It's not so much those apps per se, and I'd prefer them to be FLOSS too, rather it's the amazing content and in such rare cases, I'm happy to financially support the creators.

Does it count as paid if I donated what I think is a reasonable price?
Cause then it's KDE, Firefox, Thunderbird, LibreOffice and Gimp. I'd prefer those programs even if their proprietary counterparts were free.

I like Sublime Text and Sublime Merge and use both daily.

I would never willingly use proprietary software. I don't mind paying if I also have access to source code that is licensed foss.

Pycharm professional and Steam are pretty dope

I paid for Vuescan. There are a ton of Linux scanning apps, but pretty much all of them require editing all pictures to some extent after the scan. Vuescan applies a useful set of defaults that work for most pictures, speeding up the work flow. I had over 4,000 pictures to scan so anything to simplify that was worth it.

Lightburn for controlling laser engravers.

It's pretty much the only choice on Linux (though it is cross platform). Free 30 day trial, then ~$80 lifetime licence.

The other choice is LaserGRBL, which is open source, but doesn't seem to have a Linux port for some reason. And it has a lot fewer features, with a more complex workflow.

Dungeondraft, Wonderdraft, FoundryVTT. Battle map making, world map making, and virtual table top respectively

Does Unraid count as paid Linux itself, not just a Linux utility?

gitkraken has a lot of features that I never use. But showing the various branches and their connections as a color-coded tree is worth paying money for.

When it comes to 2D CAD/CAM, then QCad is the best. They have a GPL version, but their commercial version has a lot more features, like importing/exporting most Autocad files, and CAM functionality. For just $40 bucks, it's worth every penny. The only disadvantage it has is that it can't ever have an ARM version, because the plugin they use for Autocad files is licensed, and it only exists for x86 afaik.

Some rare games that don't scam you.

Maya, the 3d software.

Reaper DAW, for (attempting) making music

OpenAudible - because Audible cycles books in and out of the membership too fast and sometimes their phone app sucks.

I like Insync. It synchronizes with Google Drive, OneDrive, and Dropbox. It is not the only client out there but it works better than the other ones I’ve used.

moneydance for household finance tracking

SAP S/4HANA

If expensive and proprietary is what you want, it's hard to beat.

Pianoteq for virtual piano emulation with MIDI keyboards.