I've uploaded to repository a new version (0.2.7) of NextAlarm with some memory leaks fixed - but I haven't tested it (You know why...) Please try it and report if it still consumes memory...
too bad: memory usage even higher with the latest nextalarm release, and another bug: when rebooting the phone the settings window of nextalarm is always showing. htop reports 7.6% memory usage from nextalarm widget and 7.1% from the digiclock widget