AIBU to hide my expensive skincare and get cross whenever DD uses it without asking? I have specialised skincare due to Rosacea and its not cheap, yet DD 'borrows' it ! 
DD denies it as well, even though find it in her room or not where I put.
Often find my make up in her room as well.. Has plenty of her own. I wouldn't mind ironically if she asked about the make up or skincare.. Would not share but buy her similar.
I know we all borrowed mums make up as teenagers but have explained about my skin and the cost to look after it and please don't use it as you don't need it.