Once you cancel your subscription, you can still watch the content until the end of your billing cycle, whether monthly or annual.
For instance, if you have a monthly subscription, you can keep watching the content for the remainder of the month you have already paid for.
If you have an annual subscription, you can watch the content for the rest of the year you paid for.
Your Showmax account will be active even after cancellation, so you can restart your subscription anytime.