My understanding is that yes you can but you should keep a record of how those subscriptions have assisted you with the acquisition of the investment assets. If you’ve got a subscription from Motely Fool (as an example), but did not acquire any shares, then i dont think you can. On the contrary, if you do, then it seems to be likely base on my understanding of the ATO ruling below.
[Source]
https://www.ato.gov.au/law/view/document?Mode=type&TOC=%2205%3APublic%20rulings%3ADeterminations%3ATaxation%3A2004%3A%2304960010000%23TD%202004%2F1%20-%20Income%20tax%26c%20are%20the%20costs%20of%20subscriptions%20to%20share%20market%20information%20services%20and%20investment%20journals%20deductible%20under%20section%208-1%20of%20the%20Income%20Tax%20Assessment%20Act%201997%3F%3B%22&DOCID=%22TXD%2FTD20041%2FNAT%2FATO%2F00001%22
