Thanks for your question. Fonts from Typekit are available to your websites for as long as you have an active subscription. If your Typekit plan is part of a Creative Cloud subscription and you decide to cancel it, you have two options:
1) convert the Typekit portion to a standalone subscription.
We can change your Typekit account to a standalone subscription (instead of being part of Creative Cloud). The fonts would continue to work on all of your sites, and you would be billed directly by Typekit for the new plan. If you made that change today, it would be $49.99/year for the Portfolio plan that comes with a Creative Cloud subscription (https://typekit.com/plans).
2) stop using Typekit
If you cancel Typekit as well, the fonts will no longer be available to your sites once the account has been closed. The fallback fonts that you specified in the CSS stack or the browser's defaults will be used instead.