I'm just thinking digitally here, but most fonts, Wordpress themes and plugins (and other paid themes and plugins), etc. are for one installation/project.
As you mention it, first fonts are not in the same category as Wordpress which carries a General Public License (GPL) which carries the obligation to ALL themes and plugins to be produce and distributed under the exact same condition, meaning they must be GPL as well.
Limiting the number of instance installation in the case of themes or plugins for Wordpress, or any FOSS which comes with such license of freedom, is among the biggest SCAM going on in this sphere right now, as this is a violation of the GPL license which, among other things, stipulate that once you have a copy, you can freely copy and distribute it under the same license's terms. Hence, technically speaking, if a wp theme developer does limits you in the number of instances you can install, then he's breaking the license himself which they still pretend to be GPL which is an absolute non-sense.
Clourdon is NOT GPL, nor even open source if I'm not mistaken, right now, even though most of the software part of the offer are. That's not a problem at all. simply because you do not absolutely need a Cloudron box to run any of the software offer which are coming with GPL. When one pays for either cPanel or Plesk the principle is the same, the prices are always PER INSTANCE, obviously, and that is even though they too offer GPL apps installation via their dashboard via Softaculous and the like.
My 2 cents worth, tale care 🙂