ESET offers a free app ESET NOD32 Mobile Security that has all about mobile device protection. Besides protecting the gadget from malware, the app does a lot of other security jobs.
Anti-theft module allows you to control the lost or stolen phone remotely. You can delete all your data, get the location of the device (if location services are on), make it produce a siren sound if it must be nearby.
One of the most important modules is website checking. The app checks the pages you visit to make sure you’re not providing your credentials to a phishing site. ESET logs all its activity and security issues into the log file you can access.
The free version only offers basic security level. A single license applies to 5 devices (with the same Google account) and unlocks advanced ESET features. The premium version can check apps for security, access and remotely control lost devices via web interface, schedule malware scanning and do some more work.
You may purchase some extra features (like anti-theft advanced control) independently, as well as enjoy the free version as long as you wish.