Using the payments feature of QuickBooks Online is a great way to save time by letting your customers pay you directly from your invoice. I can help go over more about this feature and the fees associated with it.
When you use the payment feature there is a transaction fee of 2.9% + 25 cents per transaction. This allows the funds to be sent directly into your bank account automatically and makes the payment entry into your QuickBooks Online account. You can also find out more about payments by going here. If you don't wish to subscribe, you can still have your clients pay you through E-transfer or other means but you'll have to manually make those entries yourself.
Hope this was able to help!