POPSUGAR Must Have Box Flash Deal: $10 Off September Box or Free Gift! Posted by Hello Subscription on September 18, 2017. Subscription Box Coupons & Deals / Popsugar Must Have Box Coupons . The links in this post may be affiliate links. Read full disclosure Save for Later Notification POPSUGAR Must Have Box is having a flash sale – use coupon code FALL10 to save $10 off the September box! Check out the review of the September POPSUGAR Must Have Box to find out what’s inside! OR: Use coupon code GLAM to get a FREE NCLA MANI-ER Tool Kit with your September box!