I pay for a premium spotify account through my mobile phone, can i add the Headspace app as it asks for credit card details?
Welcome to the Spotify Community.
At the moment, the only way to get the offer is using a credit card. If you’re already subscribed to Premium through any other company than Spotify, you need to contact them to cancel before signing up for this package.
There's more info about the offer here.
Let us know if this clears things up.