免费用户还可以付费升级到Pro 50或Pro100套餐，享受50g或100g存储空间。
Power users can upgrade to pro 50 or pro 100, which provides 50 or 100 GBs, respectively, for a monthly fee.
他的看法是程序升级其实比初始销售“钱力”更大，可惜大多数商店都还不支持为升级付费的模式。
He sees application upgrades as a much better way to make money than the initial sale, yet most app stores do not support paid for upgrades.
Rails开发者可以 免费尝试RPM工具，并且可以在应用上线时升级到付费的模式。
Rails developers can try RPM for free, and upgrade to a paid subscription when the application enters production.
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