Get back into your house

Paid, then lost the page? Nothing is lost. Your castle is already standing; you just need the key back.

Find your session id

Stripe emailed you a receipt when you paid. Open it.
The link back to us contains session_id=cs_…. Copy everything from cs_ onwards.
If you still have the tab open in history, the same id is in that URL.

Stripe session id

Can't find the receipt? Email whoever runs this realm with the card's last four digits and roughly when you paid, and they can look it up in Stripe.