Subscriptions to external websites are not permitted. All resources posted on TpT must fall within the guidelines listed here: TpT Content Guidelines
In addition to these guidelines, it’s important that our Customer Experience team has access to your resources so they are able to provide technical support to your Buyers when needed. Additionally, we’re not able to support a recurring subscription payment model at this time.
If you’re ever in doubt whether something is right for TpT, feel free to contact us!