I want to make a limited item that can be purchase using VC

If the “limited item” that you said means all users under the title share one limit of this item. For example, the total number of purchases by all users cannot exceed 10. If so, although items that check [LIMITED EDITION] option can only be purchased by RM, you still can let players purchase such items with VC through some workarounds. A possible workaround is to combine Server API GrantItemsToUser with Server API SubtractUserVirtualCurrency. Limited Items can be granted to users by server or admin API GrantItemsToUser(s), SubtractUserVirtualCurrency can be used to decrement the user's balance of the specified virtual currency by the stated amount. These two Server API can be accessed by CloudScript directly. Then you can write a custom CloudScript function to handle the process of purchase.

If you want that every user has a separate limit of it. For example, everyone can purchase at most 10 items. If so, you can choose “TitleData” to store the “initial limit number”, and choose “Player Read-Only Data” to store the “Items remaining”. Server API GetUserReadOnlyData and UpdateUserReadOnlyData can be used to do the judgment and update the “item remaining”. They also can be used on CloudScript with your custom code logic.