OLM to PST conversion would be easily if user use the authentic solution for conversion. OLM and PST both are database files of Outlook application, Mac Outlook support OLM file and Windows Outlook support PST file. I suggest you before using any paid tool, must try the manual technique for conversion of OLM to PST.
Read the blog post for know more about manual procedure steps:- http://migrateemails.com/2015/09/22/make-olm-to-pst-conversion-easy-instant-and-accurate/