Yeah, Bluemaxima's Flashpoint does technically allow premium but you'd basically have to turn off autoSave and do a deathless run which is something I am not competent enough to try. It is perfectly good for runs without premium though, that's how I did my runs.

If you're interested the 2 means of running the game that do not involve editing the files that I've found are using BlueMaxima's flashpoint and playing on the website Kongregate. I was asking for permission to use and share edited versions of the .swf file to allow premium.

The premium content from Castaway 2 has been difficult to access since the death of flash. in fact, as far as I'm aware impossible. I've been working on editing the .swf file to allow for premium. Would the rest of you like to try it?

I should mention my edits have a couple quirks. One, the inventory UI doesn't expand to fit the premium button so it kind of trails off the menu. Two, occasionally windows with errors appear. As best I can tell, these are results of existing bugs not a result of my edits. Just now that I've edited it the game seems to log these errors in a new way. They're easy to simply click through.