Are the dmg skins from the spring event shop perma ?

I was wondering if the dmg skins are perma specifically the hard hitting skin as I dont get what it means by "can be used 10 days after purchase".

Does this mean that after u equip it or w/e the effect goes away OR after 10 days if u dont use it and leave it in your invent then it goes away ?

Also in the description it says "Once used it will be permanently applied" so yeah im confused f3.

I dont wanna spend 1k coins on coming temp.