This checkbox, located in the view/edit customer section of your admin for each customer, will only appear if you have this function is added to your store, talk to an Ashop Commerce representative to have this added.
Check the B2B box to activate a new member as a B2B/retail customer allowing them to see different prices when they log into your storefront with their username and password.
The different pricing is made by the extra B2B pricing field you will find activated in your products edit page.
If you only fill in this B2B pricing field and no other, then this product will only show to a B2B marked customer when logged in.
Whereas, if you don’t have a B2B price in the field, then the product will show only the retail price to a logged in B2B customer.