This depends on your subscription plan (you can see more details about our plans and pricing here: https://app.ahrefs.com/plans-pricing).
Users of both Advanced and Agency plans get updates of their tracked keywords every 3 days. The Standard Plan allows our clients to see updates every 5 days. And the Lite Plan provides weekly updates. (See the screenshot below.)
You can also check this in your Account Settings under Limits&Usage:
Please, note that if you need more frequent updates than allowed by your subscription plan you can order our Rank Tracker Pro add-on which allows daily updates.