If you install only FREE version or only PRO version on your PC, you will see the differences as described here.
However, if you install both versions on the same computer, all features on the FREE version will be unlocked automatically. In this case, you will see the two apps are nearly identical. You can continue working on the FREE version. However we recommend you to transfer all your projects to the PRO version so you will work with only one app.
Starting from version 220.127.116.11, transferring your project from the FREE app to PRO app is very straightforward.