Thank you for your feedback. We’re considering this for a future release of Azure Search.
Azure Search Product TeamMixie commented
Microsoft please implement this feature. With the ability to go up from BASIC to Standard and down from Standard to BASIC.
Justification: as a developer we do a Proof of Concept using customer data, requiring Standard. Then after approval, we remove all but sample data. We would like then to switch back to BASIC -- the customer is now paying in their own environment for Standard. So no loss to Microsoft.