Consumer identity theft protection LifeLock(s lock) is already securing the cards in your wallet. Now it wants to provide a digital version of the wallet itself. On Thursday, LifeLock said it has acquired Lemon for $42.6 million in cash. The Maveron- and Howard Shultz-backed startup began as a receipt-tracking service but expanded into the mobile wallet by adding Apple Passbook-like features. Lemon raised $8 million in a Series A round in 2012 and its app has been downloaded 3.6 million times. LifeLock will continue to offer the wallet under its own name, layering its security features on top.