When someone clicked on a CTA, and then completed a purchase or donation, how can I keep them from seeing that campaign in the future?

Use the API’s “group” feature. Follow the following steps:

1. Determine what you want to name your group (e.g. “30-day-challenge-husband”)
2. Add the code to the “thanks” page to add the group, based on https://s3.amazonaws.com/fiveqsimplepath/docs/index.html#groups
3. Note in the campaign spreadsheet to exclude those group members
4. Let FiveQ know in basecamp.