If you buy the crew package and then cancel it, do you lose all items?
I do not think so.
Because otherwise it would be a rip off.
You would pay it for a month and that would be really hard to be dishonorable.
But to be on the safe side, I recommend writing to support or asking friends who also play fn.
No, you don't lose, there will only be no further costs after a month and you keep your items.