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Tinder Launches $499 USD-Per-Month "Tinder Select" Membership
(techcrunch.com)
This is a most excellent place for technology news and articles.
In most countries it still is and basically always was illegal. I wouldn't hold your breath for the US any time soon, since half the states still can't get their shit together to legalize a harmless plant, and the puritanical pushback from the federal level if a state attempted to legalize prostitution, especially with a conservative administration, would probably be swift and immediate.