Many moons ago – way back in December of 2012 – the GO Launcher team released a new thingy called Next Launcher. As its name suggests, it's a launcher. The next one, even. It was to take the place of Go Launcher, which was essentially defunct on Android 4.0+.
But Next came with a price. A $16 price, to be exact. And honestly, not many people want to shell out nearly $20 for any app – much less a launcher they can't try first. I guess after four months on the Store, the Go team finally realized this, as it has just released a 36-hour trial version of the app.