You can’t use the tags that way. Instead use the filter hook of the plugin to get notified when a transaction happens and it is going to show data on the thank you page, then from your custom code handle the license related functionality. Using the hook is the proper way of doing what you are trying to do.
The plugin triggers the following filter hook that you should be able to use. It will pass the transaction data also:
asp_stripe_payments_checkout_page_result
The following documentation has an example of how to use it: