It is paid on the 28th of the month. From the FAQ
"How do payments work for the HubPages Earnings Program?
We provide you with a managed service which includes ad performance reporting, and a monthly payment directly via PayPal, once you’ve reached a $50 payout threshold. Earnings from the Ad and eBay Programs will be added together to help you reach the $50 payout threshold faster. The payment represents your portion of the revenue share associated with the HubPages Earnings Program advertising that has run on your share of impressions on your Hubs. You can view your HubPages Earnings Program earnings in My Account > Earnings > Balance History.
Payments will be disbursed around the 28th of the month for the previous month's earnings."