Hi brett_lenertz-bi,
If you have your bank feed connected, you can categorise the transaction directly from the feed by tapping the transaction, selecting the category and saving. When doing so, you can also create a rule to automatically categorise the subscription charges for you, both for future transactions and past. See here for full instructions on doing so depending if you are logging in via a web browser, iPhone/iPad or Android. If you don't have a feed connected, you would need to create the expense yourself; see here for steps on entering transactions manually.
-Kass