If you've initially signed up as a free subscriber to a publication and would like to view paid posts, you'll need to change your subscription plan.
To become a paid subscriber, follow these steps:
1. Log into your Substack account at https://substack.com and click "Sign In".
2. Click on your profile icon and select Account settings from the drop-down menu.
3. Navigate to the Subscriptions section and click on "Edit" next to the publication you'd like to make changes on.
4. On the next page, click on "Upgrade to paid subscription".
5. Select which paid plan you'd like to subscribe to.
Note: If you're a paid subscriber to another publication on Substack, you can subscribe with just one-click and will not need to re-enter your credit card details. If you've only been a free subscriber on Substack, you'll be prompted to enter your credit card details.