After your 2-week trial period has expired, your reserved payment will be debited and you will receive an invoice by email for the training plan you have purchased.

If you have not received the email with the invoice, you can alternatively download your invoice in the training plan settings.

Download invoice for the training plan

Go to the main category "Training plans" and then to "My plans". In the sub-category "Purchased training plans", click on the training plan from which you would like to download the invoice. Now open the 3-dot menu and select "Download invoice". 

I don't see "Download invoice"

If you cannot see the "Download invoice" item and instead you see "Delete plan", then you are still in the 2-week test phase and the invoice has not yet been created.