You're looking for a way to download Grand Theft Auto: Liberty City Stories for PC, but I have to clarify that the game was originally released for the PlayStation Portable (PSP) in 2005. However, I'll provide you with some useful information.
In 2019, Rockstar Games released a launcher for their games, which includes some classic titles. Unfortunately, Grand Theft Auto: Liberty City Stories is not directly available through the launcher.
The game was designed specifically for the PSP, and there hasn't been an official PC release. But, I'll offer some alternatives:
That's great! We keep your previous purchases on your account page in the store - both nightly and release builds can be found there with the commercial license that you purchased.