In order to use the trademarks of the suppliers, should an authorization be asked?
If a retailer buys a product for selling it, it is implicit that he will show it on a shelf or in a visible area and if it has a trademark it is obvious that this will be displayed too. This is all very normal and we could be talking about implicit leasing, therefore the retailer does not have to ask permission to the producer to display its product with the trademark, as he is authorised to do so the moment it is sold to him by the producer. It would be illegal to buy other products and show them with that same mark, but not to sell the original products with it.
The same applies on Internet, if a virtual shop of items for sale is created, no authorisation should be asked as, like a shopkeeper, even if virtual, the producer knows that in order to sell the products must be shown, no matter if it is in a shop or on the web. If, instead, we want to add particular products with certain trademarks in order to get more publicity because we stock them, then it would be advisable to find an agreement with the supplier for the use of the trademark.
Usually suppliers grant this use free of charge but on certain conditions, such as the size of the logo, a certain kind of exposure or similar; therefore, before proceeding to advertise this mark, it is wise to ask the supplier the leasing agreement, which is normally standard for all distributors and retailers.