For Ext JS or GXT, you can purchase less than 5 licenses under our Single Developer Subscription License (annual subscription) program.
For Sencha Test, yes, you will need to purchase a license that covers up to 5 developers unless you meet all of the Independent Consultant Program eligibility requirements, where you can purchase fewer than 5 licenses of Ext JS, GXT, or Test on behalf of a named client. The licenses allow you and your team to to use the software to create and/or test applications, provision their tech support entitlements and also grants distribution rights for the software/applications you have created. If you do not meet the Independent Consultant Program eligibility requirements, you must purchase a license which covers up to 5 developers. As your team grows, you’ll have up to two more licenses as your developers need them, without any additional processing.