She doesn’t have to have bought it or even have the item at all.
influencers sign up to affiliate link websites - they then get access to web links to add to their own social media to use in this way. They use a link to whatever product they like - if you swipe up or use the link and you buy the item or any other item from that website then that influencer will earn a commission from that sale. When you swipe up, the info is stored on your phone/laptop and when you go back to that site, it still acts as if you have gone in via their swipe up link (that’s Why you should always clear your cache & browser history after looking at a swipe up!!!!)
Is Meldrums case, she’s going frantic and just adding millions of swipe up affiliate links for the sole purpose of earning money off the back of it. She doesn’t have any of the things she adds the links to! It’s completely fake!!
It’s not like she’s working direct with the companies either, it’s all run via external agencies.