Already bought the subscription but it is showing it is not activated

Hello,

Thank you so much for getting in touch.

Yes, your account is already upgraded to the PRO version.

We highly recommend going through the following guide to set up the plugin completely and correctly:
https://www.youtube.com/watch?v=cQLvCBVev3I
and
https://rankmath.com/kb/how-to-setup/

Hope that helps and please do not hesitate to let us know if you need my assistance with anything else.