The Gran Turismo 6 servers will be closing in March confirms Sony Interactive Entertainment.
Though you can still play offline after this time, from March 28 online services, including the community features, lobbies and seasonal events will be shut down.
Sony issued the following notes regarding the closure of the Gran Turismo 6 servers for PlayStation 3.
Gran Turismo 6 servers axed in March
Warning Regarding In-Game Credits
If you have deleted your game data after purchasing credits from the GT Store, please make sure to install/redeem the credits again before the end of the online service to have them available in-game. The installation/redemption of credits can be done in-game from [My Home] -> [GT Store] -> [Purchased Content]. It will no longer be possible to install/redeem credits after the end of the online service.How to re-download Credits when your game data has been deleted
Even if you accidentally delete your game data after the end of the online service, it will still be possible to re-download and re-install the credits. To re-download them, go to the [Download List] in the PlayStation Store, or go to [PSN] -> [Account Management] -> [Purchase History] -> [Download List] from the PlayStation 3 XMB (Cross Media Bar).Regarding the “Track Path Editor”
With the end of the online services, the distribution of the “GT6 Track Path Editor”, currently available on “Google Play” and the “App Store”, will also end as of 28 March 2018. After the end of the online services, it will no longer be possible to transfer track data created with the “GT6 Track Path Editor” to Gran Turismo 6.
Other servers closing in 2018 include three WipEout games, the Killzone 2 and Killzone 3 servers, the Gravity Rush 2 servers and Everybody's Golf for PS3.
Source: Gran Turismo