The answer to this question depends on the project that you are about to typeset. If the project is in Paratext 8 or newer then you need to migrate to PA 6. If the project remains in Paratext 7, then you need to stay with PA 5 and should consider upgrading to PA 5.1. Note that PA 5 and PA 6 can safely coexist on your computer and will allow you to typeset both Paratext 7 and Paratext 8 or newer projects respectively.