Source: https://store.steampowered.com/news/app/3150120/view/507332586065887642

"Starting July 11, 2025, the game will no longer be free, and anyone who wants to download it after that date will need to purchase it. If you already downloaded the game while it was free – you’re in luck. It’s yours to keep forever, and you’ll continue to receive all future updates at no cost."