This morning I released 2.4.0 of my
Send to Dropbox app (send files from an Android phone to a folder in one or many Dropbox accouts).
Apart from new features I added Android Market Licensing instead of Copy Protection to this one.
* it's easy to implement
* it's hard to obfuscate against cracking
* it is absolutely limited to the Google Android Market
* No cross-licensing (buy the expensive app, get the cheap one for free) or other checking of the license-status of other apps supported.
* Be careful are the example-code uses the Base64-class that required API Level 8