1. Log in to your Streamline web app and click "Account>My Account".
2. Then, go to 'Plans and Billing' page. Then, click "Cancel Plan".
3. On this page, click "Cancel Subscription".
Note : After canceling your plan, you can still use all the premium features until the end of your current billing cycle.
As a reminder, you still have a lifetime license for assets already embedded in your projects forever. The ones you downloaded but you haven't used are not included.