There is no such limit. That only ever applied to media content (if it has DRM). You can install apps on as many devices as you want and redownload them as oft

There is no such limit. That only ever applied to media content (if it has DRM). You can install apps on as many devices as you want and redownload them as often as you want. They are bound to your account, not specific devices. If you, for example, set up a new iOS device you can just pick your iCloud backup from another device on startup and your new device will automatically download all your apps from the App Store. Mac App Store apps are similar: You can download them (as often as you want) and use them on as many Macs you own or control. They are bound to your account, not your Mac. (The sole exception might be certain iLife apps like iPhoto that come for free with your Mac. Those might be bound to the specific machine you bought, they might not, I’m not sure.)