Hello,
Thank you for reaching out to us. We apologize for the inconvenience you are facing with accessing Content AI even after subscribing to it.
If you are facing issues with accessing Content AI after payment, it might be due to a few reasons such as not refreshing the credits or not having an active subscription plan.
To resolve this issue, please ensure that you have an active Content AI plan and that you have refreshed the credits. You can do this by going to WordPress Dashboard → Rank Math → General Settings → Content AI and refreshing the credits. Here’s a screenshot for reference:

After refreshing the credits, try using Content AI again, and it should work without any issues. If you continue to face problems, please let us know so we can assist you further.
We appreciate your patience and understanding. If you need any more help or have other questions, feel free to ask.
Sources:
Resolving Content AI Related Issues » Rank Math
Hello,
Thank you for contacting us and sorry for any inconvenience that might have been caused due to that.
We can see the Content AI Creator subscription on your account. In this case, please try to disconnect and reconnect your Rank Math account again from WordPress dashboard > Rank Math > Dashboard > Help:
https://i.rankmath.com/ZvEfVb
https://i.rankmath.com/OZSwOw
After doing so, please try to refresh the credits from WordPress Dashboard > Rank Math > General Settings > Content AI and see if that works for you. Here’s a screenshot for reference:

Let us know how it goes. Looking forward to helping you.
Thank you.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.