When a charge is taken for a membership you are able to see the billing period of this charge so you can keep track of which charge is for which billing period.
To view this head to the Client profile > expand the Membership. Here you will see the 'Recent charges' - it will list the recent charge and the billing period the payment is for. For example, in the screenshot you can see that on 27th September there were two payments taken for this membership. One for the billing period September 2022 - December 2022 and one for January 2023 - March 2023.
Sometimes there might be more than one charge in one month (if there is a delay with the bank etc) so this will help to see what each charge is for!