A plan's starting day is that of the company account creation. For paid plans the starting day is the day that the plan was paid for. Every plan has a monthly cycle that starts counting from the starting day. For example, if an account is created on 10 March the monthly cycle is closing on 10 April.
Any activities on the account are referring to a specific monthly cycle.

Account administrators

You can checkout activities related to your plan by visiting the subscription page.