If you reach your monthly limit for video conversion in the Pro plan, you can book additional conversion minutes for your picdrop account at any time.
You can easily do so in your account settings under Your Plan. In the “Your Account Usage” section, you will find the “Update Add-ons” button.

There, you can choose how much additional conversion minutes you would like to add.

You will immediately receive an invoice for your new plan, with any remaining credit from your previous invoice of course being applied automatically.
After confirming the booking, your additional conversion minutes will be available instantly.