The data is located in the following places, depending on your operating system and browser(s):

  Windows Vista/7 Internet Explorer, Firefox: %AppData%\..\LocalLow\LastPass\

  Windows Vista/7 Google Chrome: %LocalAppData%\Google\Chrome\User Data\Default\databases\chrome-extension_hdokiejnpimakedhajhdlcegeplioahd_0\
  Windows Vista/7 Safari: %LocalAppData%\Apple Computer\Safari\Databases\safari-extension_com.lastpass.lpsafariextension-n24rep3bmn_0\

> Windows Vista/7 Opera: %LocalAppData%\Opera\Opera\widgets\wuid-*\pstorage\*\*\

  Windows XP Internet Explorer, Firefox: %AppData%\..\Local Settings\Application Data\LastPass\

  Windows XP Google Chrome: %AppData%\..\Local Settings\Application Data\Google\Chrome\User Data\Default\databases\chrome-extension_hdokiejnpimakedhajhdlcegeplioahd_0\
  Windows XP Safari: %AppData%\..\Local Settings\Application Data\Apple Computer\Safari\Databases\safari-extension_com.lastpass.lpsafariextension-n24rep3bmn_0\

> Windows XP Opera: %AppData%\..\Local Settings\Application Data\Opera\Opera\widgets\wuid-*\pstorage\*\*\

> Mac OS X Safari: ~/Library/Safari/Databases/safari-extension_com.lastpass.lpsafariextension-n24rep3bmn_0/
  Mac OS X Firefox: ~/Library/Application Support/LastPass/
  Mac OS X Google Chrome: ~/Library/Application Support/Google/Chrome/Default/databases/chrome-extension_hdokiejnpimakedhajhdlcegeplioahd_0/

  Mac OS X Opera: ~/Library/Application Support/Opera/widgets/wuid-*/pstorage/*/*/

  Linux Firefox: ~/.lastpass/
  Linux Google Chrome: ~/.config/google-chrome/Default/databases/chrome-extension_hdokiejnpimakedhajhdlcegeplioahd_0/

  Linux Opera: ~/.opera/widgets/wuid-*/pstorage/*/*/

  Firefox on other platforms utilizes the Firefox profile directory.

> Android: /data/data/com.lastpass.lpandroid/ by default, or /sdcard/lastpass/ if memory card is chosen.

You can back these directories up and they will contain the latest copy of your data. Be aware that on Windows, Protected Storage is used to additionally encrypt your data so you'll need to ensure that your Windows profile is also backed up. Your data is also backed up at LastPass.com, and a copy is on any other device or computer you use so this isn't required,

Your data is also securely synced with the LastPass servers. When you make updates to your LastPass account, whether in a browser plugin, a mobile app, or the website, the updates are reflected on the LastPass servers as well.

If your hard drive ever crashes, or your laptop is stolen, you can easily regain access to your accounts by reinstalling the plugin (https://lastpass.com/download.php) and logging in with the same email and master password.