Why do I have to pay to upgrade an app from the Wix App Market if I purchased a premium plan?
Many of the apps in the Wix App Market have been developed by third-party developers, and as such, the upgraded version of their apps are not included in the Wix premium plans.
Many of these apps do have a free version which can be used for your site's needs. You will only need to upgrade if you wish to use the advanced features. In addition, Wix has created a number of apps which you can use for free! You can view the apps created by Wix here.