Promissory Note

When investigators for the House of Cats were dispatched to hunt down thieves, they were given a promissory note to cover their expenses with merchants. This took the form of a scroll with golden end-caps bearing the House symbol, identifying the bearer as being in the service of the House and that the House would honour any debts incurred, and several small golden chits which also bore the symbol.
Each of the chits was a golden square with the corners angled, and one was given to merchants upon making a purchase while on House business. The merchant would then present the chit to the House together with their bill, and would receive payment in full.
Although the promissory note represented enormous buying power, misuse of its authority would swiftly be discovered by the House, who would demand an explanation. Debts incurred were connected to the honour of the house, however, so it represented a great trust placed in the bearer - and a great responsibility not to allow it to be stolen.