When using QuickBooks, you can enter any number of entries since the data it can store in the cloud has no limit. But as you go along, you may experience a delay while working with us as your business is growing and you also need to record a lot more entries.
For a awesome experience with QuickBooks, you can consider the following requirements: System requirements for QuickBooks Online.
Additionally, I've also included this helpful article for the steps in keeping your account active: How to update your subscription and billing details?
If you have any other questions, please let me know in the comments. Stay safe!