Agreeing to keep your portfolio of items for sale exclusive to codesellmarket allows you to almost double your earnings. You can still sell other items elsewhere (on other marketplaces, your own site) but any items that you place on an codesellmarket site must be exclusively sold there.
Specification is set at the account level and is optional. While the exclusivity applies to your account, it only applies to items (and related items) that you sell through that account. In other words, being an exclusive author with us doesn't mean that anything you create has to be exclusive to CodeSellMarket. It is the item, not you as the manufacturer, that is exclusive to CodeSellMarket.
If you want some of your items to be available exclusively and others non-exclusive, you can create two accounts: an exclusive account and a non-exclusive account.
You can change an account's exclusivity status at any time through your account settings, then you will be able to offer the item in that account outside of CodesellMarket and the author fee you pay to CodesellMarket is non-exclusive.CodesellMarket will change into pace. The exclusivity option takes effect immediately.