Since Android L is in a very early beta, and the average user can't nor is advised to install it manually, the otherwise attractive keyboard was, at first, seemingly reserved for root users, who could snatch the .apk off xda-developers and simply install it on their rooted device. Thankfully, however, a certain developer made the L keyboard available as a third-party app on the Google Play Store, allowing even non-rooted handsets the privilege of messing around with it. Unfortunately, if you haven't taken advantage of this opportunity yet, you might be out of luck.
That's right, as some of us expected, Google apparently considers this to be infringing on somebody else's intellectual property (and in this case, their own), and have taken down the app, reports Shen Ye, the developer of the app. Ye is none too happy about it, and feels "Scroogled", though we'd be surprised if he wasn't aware of the risks when publishing the app, or at least later, when the app started trending (it was downloaded over 800,000 times, according to the dev). In any case, this leaves most of us with no easy option of getting the Android L keyboard, and unless you're willing to get your hands at least a little bit dirty, you may, indeed, be out of luck.
source: +Shen Ye