Anki is an app for flashcards. It works online and on different platforms, including mobile. You download the app, select a flashcard "deck", and start memorising.
The app presents a card: this might contain a hint like "1 Timothy 5v18". You must then remember, say, the contents of the specified verse.
If you remember correctly the card won't appear until the next day. Get it right again and it won't appear for a week, then a month, and then a year. Get it wrong, and you'll be shown it again and again till you get it right!
Cards that you get right or wrong are sync'd to the web so you can pick up where you left off on any device, any time. There's even a website version so you can carry on studying from a browser.
As well as Bible verses there are decks for Hebrew and Greek letters and words, and also grammar. Some are arranged in order of word freqency in the Bible, which allows you to start recognising and reading words relatively quickly.
It's a great tool, and one that can be really helpful to your own personal Bible study.