Complex sentence: Bills of credit were used as currency in addition to providing funding for the province's expenses, and repeated issuance of them had an inflationary tendency to devalue them relative to the pound sterling.
Split into simpler sentences: Bills of credit, in addition to providing funding for the province's expenses, also circulated as local currency. Issuance of large quantities of such bills had an inflationary tendency to devalue them relative to the pound sterling.