7 - Day Trial

When I opened my first Hectech Crate I received a_ Katarina Slay Belle Skin_ that looked amazing! So I started a 7 - Day Trial with this skin and after I finished my match I wanted to Permanently Unlock the skin so then I looked back to the Loot & Craft Inventory menu which is where the skin is supposed to appear and I did not find it. Id like to know if this is a bug or its supposed to happen because it would not make sense that you cannot permanently unlock a skin during the trial.