The most likely reason is that they started the checkout process, and dropped out somewhere along the way. It happens, (can't find your credit card, don't have all the right details to hand). We've all done it at some point.
Why not drop them an email and ask if you can help. Go to their member page in the admin panel and click on their email address to send them an email.
How can I find out if I have members who dropped out?
On the member list page, you can filter by:
- Has Logged In: Yes
- Not covered by current subscription (although note that people who have placed an order for a sub, but not yet paid are not covered)
- Linked since xxx (if you want to find the recent new members)
Then have a look at the individual member's page and see if they placed an order.
