If you are upgrading to a higher level product (e.g. BBC SO Core to BBC SO Professional) your price will be the difference between the two versions at the time of purchasing the upgrade.

In a sales period, the price that is deducted is the current sale price of the library you own. The discount will be better though, as the sales discount price is applied after your specific price is calculated. In simple terms this is:
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​(Pro Library - Core Library) - Sales Discount = Your Price
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If you are logged into your account, your price will be shown on the product page automatically as well as in your cart, as the website detects what you already own.
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