On DigitalOcean, you only pay for what you use. $5 per month for a 512mb droplet is simply the most it would cost for a month. If you check out the pricing page, you’ll see all of plans at both the hourly and monthly rates. For instance, the 512mb droplet costs $0.007 / hr. Though if you run it all month long, we simply charge a flat $5 as thats easier for everyone.

So if you launch a 512mb droplet and test it for a half hour before destroying it, you’d only be charged a penny.