Starting on November 22, 2013,[1]Mojang began to publicly release testing versions of full updates to Android users who opt into the beta program, in order to get major feedback, especially for bug reporting. This enabled the official updates to be considerably more stable.
You have to opt into beta testing to join the group. Development updates appear as normal updates in the Play Store. As SMP only works with devices of the same version, using the pre-release means that you can only enter servers who have the same development build. If you decide to opt-out of the testing, you can do so by going back to the beta testing page, opting out, and the official release of Minecraft Pocket Edition can be installed to your device again. On July 17, 2015, the PE Beta Community on Google+ was removed as they "were trying to limit spam amount we get from people who sign up not to test but to advertise."[2][3][4]