Why not just use a spreadsheet?

Because they can’t remind you or ask for the renewal.

UGCPing vs a spreadsheetA spreadsheet can't email you when usage rights are about to end. UGCPing can, and it drafts the renewal email too.
UGCPing vs a calendarA calendar can flag a date, but it doesn't know the deal. UGCPing keeps the dates and fee together and drafts your renewal email.