Every time a donor's credit card is charged, a payment transaction is created. In your nation, each charge creates a separate donation listing. When the charge is part of an active monthly donation, it is also connected to a monthly plan.
Viewing donations in a profile
In the Finance section of a donor's profile, the Donations section lists every payment made by the donor. For example, last month John started a $25 monthly donation in my nation. John has made two payments. In the Finances > Donations portion of his profile, I can see both payments listed:
In Finances > Monthly plans, there is one listing for his $25 monthly plan.
If I click the pencil button on the monthly plan, I'm taken to the dashboard of this plan. On the right side of the dashboard, you can see a list of all donations associated with this particular plan:
All of this is happening within the People section of my control panel. If I go to the Finances section, I can review all donations made in my nation. Filtering the Finance section provides a great way to sort financial transactions. Additionally, Finances > More > Monthly plans lists all monthly donations, and Finances > More > Installment plans lists all installment plans.