private void cleanupService() {
        if (mService != null) {
            try {
                mContext.unbindService(this);
            } catch (IllegalArgumentException e) {
                // Somehow we've already been unbound. This is a non-fatal
                // error.
                XLog.e(TAG, "Unable to unbind from licensing service (already unbound)");
            }
            mService = null;
        }
    }
Unbinds service if necessary and removes reference to it.
android/android_framework/base/src/main/java/com/google/android/vending/licensing/LicenseChecker.java