$Unity Software (U.US)$
Take Unity's Personal and Plus versions as an example: if you are an indie developer, once the game you created using this engine earns more than $200,000 and surpasses 200,000 installations, you will need to pay Unity $0.2 per month for every new user who installs the game.
Unity Pro and Unity Enterprise versions charge installation fees based on a tiered system for additional users beyond the included quota. The standard monthly rate applies to regions like the United States, Australia, Austria, Belgium, Canada, Denmark, Finland, France, Germany, Ireland, Japan, the Netherlands, New Zealand, Norway, Sweden, Switzerland, South Korea, and the UK. Emerging market rates apply to all other regions.
Look at the table below. Essentially, it’s pushing those free or low-cost users who are making money to upgrade to the Pro or Enterprise version—this isn’t unreasonable. China is still charged at the emerging market rate, which is only 10% of the standard price, so why would anyone want to stop using Unity?!