Credit card: Your Royale membership will automatically renew each month or the following year (depending on your renewal plan) on the same day you upgraded. For instance, with a monthly plan, an upgrade on January 13th will renew each subsequent month on the 13th. If you've upgraded on the last day of the month (i.e. Jan 31st) your membership will renew on the last day of each subsequent month (i.e. Feb 28th, Mar 31st, April 30th, etc.). An annual plan will renew the next year on January 13th.
A Royale membership upgraded with a prepaid gift card will not be automatically renewed. Here is what you will want to do in these cases:
PayPal: If you are not set up with automatic renewals, you can do so easily at anytime from your Account page.
Prepaid Gift Cards: Update your Account page with payment information on or before your expiration date.