That seems strange. Here's a link that you could look at to help you figure out why that is the case: https://support.spotify.com/account_payment_help/subscription_information/how-do-i-check-my-subscrip...
This link is "Why isn't my Premium subscription working?": https://support.spotify.com/article/i-pay-for-premium-why-am-i-on-free/
If you want more assisstance with this matter, I'm sure you could bring it up with the Spotify support team: in this link.
Hope this helps!