Alfred version 2 was superseded by Alfred 3 in May 2016. While Alfred 2 is no longer actively developed, it will continue to receive security/essential updates at this time.
Alfred 2 is supported for use on macOS 10.9 to macOS 10.13 High Sierra. If you are using macOS 10.14 Mojave, you'll need to use Alfred 3.
Using Alfred 2
For users who need to re-download Alfred 2, you can find it here: https://cachefly.alfredapp.com/Alfred_2.9_446.dmg
While the documentation on the Help site has been updated to reflect the changes in the new version, you'll find answers to your Alfred 2 questions in the documentation too.
Upgrading to Alfred 3
To make your upgrade as smooth as possible, you'll see the Migration Assistant when launching Alfred 3 for the first time, which will help you migrate your Alfred 2 preferences with you.
We also offer a discounted upgrade from Alfred 2, so you can enjoy the new features too! To upgrade, enter your Alfred 2 Powerpack license details here: https://www.alfredapp.com/powerpack/upgrade/