Depending on what type of account plan that you have, each plan is allotted a maximum number of entries for each of the calendars in that account. Free Basic accounts get 500 entries and paid Solo and Team accounts get 3,000 entries. “Calendar Entries” includes both Day Notes and Events.
If you exceed the number of calendar entries allowed to your account, you will not be able to add any more calendar entries until you erase some of your older entries or add more space to your account.
If you want to see how many calendar entries you are currently using for calendars in your account, you can click on the gray “Customize” button above your calendar and then click on the “Data Management” tab. Then you'll need to click on the "Backups and calendar clean up" tab. Your current number of Calendar entries will be listed at the top of the white panel on the right side of the screen. Follow the steps in the image below:
If you have multiple calendars in your account you can see the breakdown of how many entries are being used in each calendar in "My Account." Follow the steps in the image below: