If you signed up for FindThatLead before May 2018, your credits will be refilled on the first day of the following month.

If you signed up after May 2018, your credits will be recharged 30 calendar days after the activation or purchase of your account.

You can check the refill date in your settings panel as shown below:

In addition, if you need more credits, you can use the credit recharge option that you can find in Settings.