Our accounting software was out of maintenance and needed to be upgraded. We spent $10,000 with a third party to upgrade the system. This was all service hours on their part. Can we amortize the $10k over the useful life of the software

yes but what is the usefull life of the software? prudence would suggest that these expenses should be written off quickly as software, particularly old software, has a limited life due to obsolence of both the software and the computer operating systems