To use dynamic content, you'd have to have a segmentation. You could create a segmentation with 2 segments, 'used product in past 30 days' and 'not used product in past 30 days.' Just keep in mind that you can only have 20 segmentations, so if this is not something you'd use to generate dynamic content frequently, you may just prefer to create 2 emails and use the add choice on your send email flow step.
ie: flow step - If member of list (or if used product in past 30 days is true) send email A, All else, send email B.
Hope this helps!
Tara