For payment terms, you have the option to enable a setting where users are allowed to pay more than the standard subscription price. More information about this is available here.
There is no separate report available for users who have a subscription in which they've paid more, but you are able to get this data from the Transaction log report.
Each of your subscriptions has a standard price. When the price in the Transaction Report for the individual term is higher than the standard price, this user has chosen to pay more.
For example, if a term has a standard price of EUR 1.00.
Apply a filter to include options priced above EUR 1.00 to find all transactions where users paid more.