• How can I add an additional contact to my client?
• How can I add a client?
• How can I print my client list?
• How can I restore deleted clients?
• How can I add additional information about my client?
• How to check the details of my clients?
• Why am I not allowed to add any more clients?
• How to add notes to my client?
• How can I delete a client?
• How to change my client's tax name and tax number?

You can't add more clients because you've already used the full amount of clients that your account plan allows you to have.

If you want to have more than 3 clients you have to upgrade your account to a Solo or a Pro account.

On the Solo account you can manage up to 35 clients and on the Pro account you can have unlimited clients.

You can read here how to upgrade your account.