You are provided with a free 30 day trial when you first create your WorkSked account. However, if your account has 5 employees or less, you can continue to use it for free after the 30 days have expired.
If after your 30 day trial, you have more than 5 employees, you are required to upgrade to a pay account. Until you upgrade, you will not be able to add new employees or publish schedules. You will always have access to your account but its use will be limited.