You should read this blog before using any tool for ost to pst conversion. In this blog you'll know more about free method to convert ost to pst. Before using any paid tool you should once try free manual method. In this blog I'll teach you to freely convert ost to pst without any cost.
If you want to convert ost file into pst method by paid method then reading this blog is very helpful for you because it also mention such paid tool that can easily Convert their OST email to PST file format. with this utility user can also Repair their corrupted OST file and Recover deleted OST file data items like: email, notes, contact, attachment, sent item, delete item and journals etc.
Read this blog: OST to PST Conversion