You already track what you owe each sponsor in a spreadsheet. The problem is that a spreadsheet can’t prove anything — the other side never confirms it, so at renewal it is your word against their memory.
Free for one event. Your partners never pay and never need an account.
Every deliverable, per sponsor, partner or client. Before, during and after the event.
Attach a photo or a document as you go. Your team does this on a phone, at the venue.
One link, no account needed. Their confirmation is the part a spreadsheet can never give you.
Not connected yet — the app database environment variables are not set on this deployment.