Thanks for your interest in Typekit! There is information on this in our font licensing FAQ:
> Does a Typekit subscription allows us to use web fonts for our client's websites - or any for our own websites?
You may use any Typekit subscription to add web fonts to your own site(s), including the Free plan.
If you would like to host web fonts for client sites, however, you will need a Typekit Business plan. This type of reselling is not allowed on the Free or annual Typekit subscriptions:
> If not what is the best way for our client to license Typekit fonts?
Your client also has the option of setting up their own Typekit subscription to host the fonts for their site.
I hope that this helps; let me know if you have any other questions.