Where can I modify the direct link of the form?

From what Pricing Package I can modify the direct link of the form ?

And how much can I modify it ?

Regards

You can use a custom URL that uses the username of the account and the title of the form. Here's a guide: How-to-Create-a-Custom-URL-of-a-Form.

Please take note that the custom URL is available to any plans, free or paid.

You may also use custom domains here in JotForm. Please check this guide: How-to-use-Custom-Domains-with-Jotform.

Hope that helps. Thank you.