AccuPOS (http://www.accupos.com) makes Point of Sale software that integrates with various accounting software. AccuPOS acts as a reseller, bundling Wasp's Labeler software with their product.
Wasp Tech Support can help with Labeler to a certain extent regarding linking a label file to an external data source (e.g. QuickBooks), as long as the customer knows what data source to connect to. It may be necessary for the customer to contact AccuPOS Tech Support for assistance. AccuPOS usually supplies a label file (.LABX) that is pre-configured to link to their data source.
AccuPOS contact info from their website (as of September 28, 2015):
North America Support: