To upgrade basic or pro version from free version. You need get version with Plan you want and download file source code.
Download source code #
You can select version you want and click download update (if you want update from free version) or install (if you want install new clean version)

Update #
You can click Upload button -> select file source downloaded and waiting update. After update, system auto reload page to get new version.

*) If you still can’t upgrade from backend. You can upgrade via ftp (file manager with cpanel):
- Connect FTP account (by filezilla or any software ftp client) and go to folder: wp-content/plugins/product-designer-app
- Download file update version -> Unzip file to a folder and open with filezilla before upload.
- Start upload overrite all files to upgrade.

Also, You can install new update version by file source code install by step like install new by file