You have the flexibility to re-customize your subscription anytime during the month. This way, you can always have the right plan for your needs. Plus, if you ever have any unused bandwidth or time in your current plan, you'll be credited for it!
Just so you know, you can only have one subscription at a time. So, if you want to upgrade to more proxies of the same proxy type, choose the final number you'd like to have in your plan. For example, if you currently have 100 proxies and want to upgrade to 250, you'll keep your original 100 proxies and receive 150 more.