Many ReadyAPI users formerly used SoapUI OS, SoapUI Pro, LoadUI, or LoadUI Pro. Here are some guides on how to move from those environments to ReadyAPI.
ReadyAPI projects are fully backwards-compatible. You do not need to perform any additional actions when moving to a later version. Your preferences and workspace settings will be imported automatically.
Projects created in SoapUI are compatible with ReadyAPI. Open the project in ReadyAPI to convert it to the new format and use it immediately.
After you convert your project to the ReadyAPI format, there will be no guarantee that it can be opened in SoapUI. Also, there is no way to move ReadyAPI's features back to SoapUI. For instance, all Pro features or performance tests are not backwards-compatible.
For information on interface changes, see Migrating to ReadyAPI From SoapUI Open Source.