GTA 4 is currently not available for purchase on Steam, at least for now.
As noted by resetera, " GTA 4 Still on Steam, but the buy button has been removed.
The full version of the game has also been removed from sales, but the standalone expanded version of Grand Theft Auto: Liberty City is still available for purchase.
As of press time, Rockstar Games has not provided an explanation of the inability to purchase the game.
The culprit may be music licensing, this is not the first time a music issue has occurred in the game.
As early as 2018, music licenses for certain songs in the soundtrack expired. This forced Rockstar to update the game and delete a large number of audio tracks.
In 2014, a patch for the PC version of Grand Theft Auto: San Andreas removed 17 songs from the game's original soundtrack. In 2012, Grand Theft Auto: Sin City was temporarily removed from sales on Steam so that developers could remove ten songs from the soundtrack.
However, since no explanation was provided, all of this is speculative at the moment. Neowin pointed out that the Xbox 360 and PlayStation 3 versions of the game can still be purchased at their respective stores.