Hello there, sachingu.

We don't have a specific time yet when the feature to be able to enter another variable and enter the month and year inside the description of the recurring invoice. Meantime, you'll want to use the workaround shared by Fiat Lux - ASIA.

You can always log in to your QuickBooks Online account and click the notification bell at the upper-right for more updates on our features, or you can click here. 

Feel free to post your questions here if you need more help. Take care!