Hello @Johnny Tsang ,
Thank you for reaching out to the Microsoft Q&A platform. Happy to answer your question.
The assessment screenshot showing Azure VM readiness (requires Visual Studio Subscription) only means that you need Visual Studio Subscription for getting the support for your client (Only Client OS like windows 10, 8, 7) operating systems in case of any issues with client OS.
It is not a mandatory subscription type for azure migrate. When azure migrate, assessment adds a readiness category like "Conditionally ready for azure" it only means we are not stopping you from migrating this VM with client OS to azure, however if for some reasons the machine gets into any issues like boot OS, any OS related issues after migration, azure VM support will not support you without a proper subscription. You need not worry about this at the moment during assessment/migration.
Please note, the Visual Studio subscription support for specific client operating systems is mentioned in the following link https://learn.microsoft.com/en-us/azure/virtual-machines/windows/client-images
Hope this helps.
--please don't forget to upvote and accept as answer if the reply is helpful--