Does it cost anything to use Keepthescore.com?
The basic functionality is free. You can create boards for free, but some features like removing ads and image upload require a subscription.
You do not need to pay to use this app. However, paying will remove advertising from boards and unlock certain features relevant to power-users. You can read more on the pricing page.
How do I cancel my subscription?
When logged in, click on you name at the top right and then on My account. If you have an active subscription, you'll find a prominent button labelled "Cancel your subscription".