A network of consumer authorities that took up those complaints "found that Tinder applied such personalized prices without informing consumers, which is in violation of EU consumer law," the European Commission said in a statement on Thursday.
"Personalizing discounts without explicitly informing consumers is unfair as it hinders them from making an informed choice," it said.
For instance, a 2022 study in Sweden showed that Tinder applied 36 different price levels, charging some users the equivalent of $3 (2.7 euro) a month while others were asked to pay as much as $36 per month.
The users in Sweden and the Netherlands were offered only the subscription fee automatically determined by the company with no possibility for them to compare against the other prices.
And until April 2022, younger users were often offered discounts on Tinder's premium service, while older ones were hit with higher fees.
The commission in July 2022 opened an investigation against Tinder over its practices.
In its statement, it said that, after dialogue with the company, Tinder vowed that by the middle of April this year it would cease personalized pricing based on age without informing users clearly beforehand.
It also undertook to tell consumers that discounts it offers for its premium services are automatically differentiated and explain to them why that happens, for instance because they declined to purchase a service at the standard rate.
The commission said the Consumer Protection Cooperation Network that took up the Swedish and Dutch cases would monitor how well Tinder lives up to its commitments.
California-based Tinder is owned by a Texas company, Match Group, that runs a number of other dating apps around the world, including Hinge, Meetic, OkCupid and Plenty of Fish.
Match Group says Tinder has 10 million paid users worldwide but their numbers are slowly declining. It also says it integrates artificial intelligence into some of its services.
In Europe, the group has 4.5 million paying users for its apps. Tinder, worldwide, brought in $1.9 billion to Match Group's global revenues of $3.4 billion.