Please I have mistakenly uninstalled my WordPress from my server and upon reinstallation the demo data is available. does it have anything to do with the license? please how can you help me fix this
If you uninstalled without backing up at first, then you probably lost your own data. However, lets wait for an answer from a WordPress expert.
If the theme requires theme license registration then you have to register the theme license using your purchased code (license key). Some theme require envato market api personal token. you can check the theme documentation hopefully you will get necessary help.
Otherwise contact the author of your purchased theme, theme author will assist you.
How to contact an author to get support or for any technical query:
If you’re looking for some to restore your data ( files/database ), you can contact me and I’d be happy to help you ( paid job )