As much as you want, as long as it’s within your Kit Daily Spend Limit. You set this up when you were onboarded to Kit. You can check and update this limit in "Boss or Child account > Your Child's settings > Update daily spend limit". Note that the spend limit applies across a 24-hour period (i.e. a child cannot spend more than the daily spend limit within a 24-hour period). Pending transactions from previous days contribute towards the daily spend limit.
If you’re shopping in store, you’ll need to enter the Kit card PIN for any purchases over $200. If your kid has forgotten their Kit card PIN, as a parent or guardian, you can reset it by clicking the top left menu button, then accessing the kid’s settings page. From there, choose ‘Update card PIN’.