aws-iot-button | Simple example of sending AWS IoT Button events | Cloud Functions library

So there's a two things I see that should be done differently.

First, you have this:

createTopic('aws-iot-button-sns-topic', (err, topicArn) => {

Right now your function is creating needless topics without ever deleting them, this is a problem. You should instead create the SNS topic externally and reference it here by either using Lambda environment variables or hard-coding the SNS topic arn. Or, first check if a topic with that name is already existing, and don't create it if it does.

Second, Lambdas don't run for longer than 900 seconds (15 minutes), so checking whether or not the script has been running for >24 hours is impossible.

What you should do instead is create a CloudWatch event trigger that runs every 24 hours using cron. This way, your lambda will run exactly one time every 24 hours (or whatever event you configure), and in the code you simply have to send the message once. There will then be no need to check what time it is or how many you already sent, since you know the event trigger happens only once, therefore your message gets sent once and your Lambda ends its execution right after.

The essence of Lambdas is they are short-lived and stateless, so design your service accordingly :)

Edit: After the comment, I understand the use case more...in this scenario, where the Lambda gets executed by IoT, I would personally store the previous execution time in SSM parameter store or DynamoDB, and then whenever the Lambda gets executed, I would get the value, check if 24 hours passed, and send the SNS if it did. You will have to do this because Lambda won't know otherwise when the last execution time was (and make sure to only update the last execution time on a successful SNS publish call, that eay you're sure that you sent a message that day)