Monthly grants and rollover rules

Credits are granted automatically each month according to your plan. Whatever you don't use rolls over for one more month, then expires. That means you can't stockpile indefinitely, and you can hold at most twice your monthly grant.

They arrive on the day you signed up (or the day you paid, on a paid plan), not on the 1st of the calendar month. Start on August 15 and they land on the 15th every month. If a month doesn't have that date (your day is the 31st but the month ends on the 30th), they land on the last day of that month and go back to the original date the month after. The exact date and time are shown as "Next refill" under Settings > Credits.

Upgrade and the difference arrives immediately, and that day becomes your new anniversary. If a reset is coming up soon, it's worth using what's left.