Protect data in memory flash

You can:

• Use E.setPassword to stop anyone logging in via the REPL
  
• Use something like LoopbackA.setConsole() to move the REPL somewhere it can't be accessed by anyone at all
  
• Store your JS code in flash memory as an encrypted string and then decrypt that into RAM at runtime.
  
• Minify/obfuscate your code using standard JS tools - this is the easiest (minification is an option in the IDE) and realistically it's going to make your code very hard to reverse engineer, while also using less memory.
  
• Make your code check getSerial() to ensure it will only run on one device
  
  

I'd suggest a combination of the them - making the REPL inaccessible, minifying your code, and checking the serial number should give you pretty good protection, and even if someone attaches a debugger and completely reads out saved code and writes it to a new device, it will still refuse to work.