Certainly the Google's LVL is the standard for license verification when selling through the official Market, but with the influx of tablets that don't have access to the Market, I'm beginning to look at making my app available through other distribution channels.
How should one attempt license verification when selling through distribution channels other than the Market?
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In that case you need to implement your own DRM mechanism. Trust me its no use using anything other than Android Market for distribution. Not many have it and for paid apps, Marketplace takes a lot of headache off you. I dont think there is any mature Android Distribution Channel other than the Marketplace
After some more research, what I've found is that there really is no present alternative. However, I did receive an e-mail response from AppsLib indicating that they are a few weeks away from releasing their own implementation of LVL for the AppsLib Marketplace. They claim that "when it is released you will only need to add a few lines of code to your apps for it to be compatible with both Google and Appslib."