With a subscription, you get pro version to all paid content of Timemark. You can still use for free without Timemark Pro.

After you confirm your purchase, your iTunes account will be charged for the initial subscription period fee. Your subscription will be automatically renewed unless you turn off auto-renewal at least 24 hours before the end of your current subscription period. Your subscription will be renewed for the same period as your initial selection.

Your account will be charged for renewal within the last 24 hours before the end of your current subscription period.

You can turn off auto-renewal in the account settings of Apple at any time.