Anki

1. Automate Community
2. Productivity

It will open the Anki Review (of your current deck) everytime you unlock your phone.
Really helpful to get your reviews done.

Note: When you unlock your phone and Anki is opening and immediately closing, then just open your Ankidroid and open the deck you want to study, then close it. The next time you unlock your phone, it'll work fine.
You can change your current deck in this manner.

Rate and Review if you like it so that it can reach other people!