If you need to export OST files to PST files, you should use the well-known eSoftTools OST to PST Converter software. It contains special characteristics that make it easy to convert single or numerous OST files at the same time. It can convert a large number of ost files into a single pst file. You may also try its free trial pack versions to see how well it works by converting the first 25 ost items from each folder to pst or other appropriate file formats.
Read More:- Export OST to PST files