Unfortunately, purchases made prior to being a Drop member do not qualify for points.
When it comes to earning points on Power offers, we award points based on the transactions we see after you've linked a card to Drop. When this information doesn't appear in our internal systems, we aren't able to award points for these purchases.
Similarly, purchases made with the brands available for in-app offers will not qualify for points. It's required for members to shop/sign up through the Drop offer link to qualify for these points, and if this step has been missed or the purchase was made before being a Drop member, it will not qualify to earn points.