Purchases an item that is either an auction with buy it now option, a fixed price item, or a shop item. Returns all the buyer's transactions that have taken place within the specified constraints. The buyer in this case is the user for which the call is made for. Transactions are matched on their creation date. When MinTransactionDate is omitted the last 60 days are returned; when MaxTransactionDate is omitted there is no upper bound. Returns seller information for the specified user. Returns bidding information about auctions that user has placed a bid on (but not won) during the specified period. Gets items that are in the user's memorylist. Adds items to the user's memorylist. Removes items from the user's memorylist. Updates the paid status flag on the specified transactions.