Android :: Copy Protection & License Key Management

1. When the "copy protection" checkbox was first introduced on Android Market, I heard about a lot of issues with people not being able to download etc. Have those issues been resolved now? If I turn on copy- protection on an app with over 10K active users, do I risk a major rebellion?

2. I'd like to sell my app on other stores like slideme, andappstore and handango. Since some of these just redirect the user to your own site to download the app, there needs to be a license key that authenticates the user and unlocks his app. I saw that andappstore has a framework for that (not sure if that will only work with them or is a generic solution). I'm looking for a free, generic licensing solution. Is there one that you know of or use? My concern is to not throw in a wrench in the process of user download and use of the app, where I start getting a ton of emails from people whose keys arent working or asking for new keys etc, where license support turns into a full-time activity.