That link expires when your session does — but you're not out of options.
To make sure you have valid parking, you'll need to start a new session. Here's how depending on how you originally paid:
Paid through the app? Head back to the zone in the app and purchase more time from there.
Paid via QR code? Try reopening your phone's browser and navigating back to the payment page. If that's not available, the app is your next best option.
Don't have the app? No download needed — you can access HONK through the web app at https://parking.honkmobile.com/signup. Create an account, find your zone, and purchase your session from there.