I've already payed for the game but for some reason I can only play demo. I tried to figure it out myself but that didn't work. I thought it was because I needed a Mojang account but then I saw that you guys were converting it to a Microsoft account which I have. then I check that it tells me I have to pay again when I already did.
Linked issues
Comments

Thank you for your report!
We're tracking this issue in MCL-16570, so this ticket is being resolved and linked as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki
-- I am a bot. This action was performed automatically! Please report any issues on Discord or Reddit
This report appears to be a duplicate of MCL-16570, which was later resolved as invalid because this is an account issue and the bug tracker is unable to help you. Please see the Mojang Studios note attached to the parent ticket to potentially fix this issue.