check here www.guitarhero.com
As of June 1, 2018, iOS versions of the Guitar Hero Live game for mobile will no longer be available for download via the app store. However, if you currently own the app and have it installed on your device, you can continue to play the GH Live mode on your installed device. Note, if you update your iOS software, the app may no longer be supported.
They remove the app from ios store!! and 1st decembre they will switch off all servers about GHTV so you can play only 42 songs in the off line mode and stop. it is a pity but i think it is the end for this game and activision doesn't care about GH fans!!