Microsoft also offers a free 60-day trial of Office Professional Plus 2013. RELATED: How to Extend Your Office 2013/365 Trial to 180 Days Office Professional Plus Trial – 60+ days You’ll have to cancel your service before the free month ends or Microsoft will start charging you $9.99 per month. The only downside here is you’ll have to provide payment details at the time of download. Microsoft offers a free month of Office 365 Home Premium, which allows you to use Office on multiple PCs and Macs. RELATED: What's the Difference Between Office 365 and Office 2016?