Is that even legal?

Beth once posted about intangible transitions - when does a person stop being one-dimensional and start being a dynamic character in one's life?
Speaking of intangible transitions, I got this email last week from Serena, a woman at Palazzo Rucellai:

Dear students,
This is to remind you that tomorrow is the deadline to have your money back from the canceled match: Fiorentina-Napoli. After this date I won't refund you any more
Ciao
Serena

This got me to thinking...at midnight tonight does the money really stop being mine and transition into being yours? Is that even legal? I'm pretty sure that the 20 euro I paid you is still MY 20 euro even after midnight on the deadline. However, if it is legal I'd like to say the following:

Dear Mom and Dad,
This is to remind you that tomorrow is the deadline to withdraw money from your bank account. If you do not withdraw all of your savings by tomorrow, I will not refund you after it magically becomes mine at midnight.
Ciao,
Rachel