Why is the subscription renewed despite cancellation?

The calculation of deadlines and runtimes in the plenigo system is carried out in months, days and years. A new subscription step/accounting period always starts with a daily change, meaning at 12 am. The customer, therefore, has to cancel in good time. A successful cancellation depends on the defined cancellation period of the offer.
Example:
Offer Step 1
runtime: 1 month
Cancellation period: 1 day before the end of the subscription period
start date: 23.12.2020
end date: 22.01.2021

This means that the subscription ends with the end of the first offer step, on January 22nd. From January 23rd onwards, the subscription will be charged. Therefore, the customer has to cancel the subscription on January 21st, at the latest, as the cancellation period is 1 day before the end of the period. If the subscription is canceled on 01/22/2021, the cancellation is not effective as 01/22/2021 is the last day of the runtime and is not within the defined cancellation period.
In this case, the subscription must be canceled until the end of the 01/21/2021. This applies regardless of whether a customer purchases the subscription on 12/23/2020 at 12 am or 11:30 pm.