Preventing Over-Purchase Errors

H @Peléton ,
It's great to see you in the community!

I think the best approach might be to start by creating a segment based on the specific requirements, for example, like this (if you're using Shopify):

Then, create a flow from scratch and set the segment as the activation trigger, like so:

Afterwards, maybe add a delay that you think is appropriate, short enough not to overwhelm the user but not too long either, so they don't feel ignored. Also, because from what I understand, there might be an error but it's not certain (correct me if I'm wrong). Here's a screenshot of how the flow might look:

I believe the message should be as non-commercial as possible. An idea for the layout could be something like this (ignore the focus on the expired trial), but with a simple product image, clear text, and a prominent CTA for the desired action (contact us, write to us, etc.).

I hope this helps in some way.
Wishing you good sales!