Purses files contain transaction history of your purses, as well as the WM internal mail history. You don’t necessarily have to have the file to use WM Keeper CLASSIC. You can always make a new one when you start WM Keeper.
When you launch Keeper and if it cannot find the file, the following dialogue box will appear:

You can either browse for the new location of the file, if you moved it, or, if you don't have it, Keeper can create a new one. In this case the transaction history will be restored (at least all records for the last 3 days, but usually more than that). Correspondence history will be lost since it is stored on your computer only.