Do your homework before deciding to purchase an ITAM/SAM tool. Make sure to check if you already have an existing system/tool being used in your organization that could fulfill your needs. Don't get bogged down with features and customization possibilities. Don't pay for more than you need.
Overall, when selecting a tool to support your ITAM program you want to look for an asset repository that will centrally hold hardware, software, and usage information, have the ability to integrate to adjacent IT and business systems, and be able to both import and export data. In regard to SAM, you want to include being able to track software licenses, software contract agreements, downgrade and upgrade rights, ability to do software reconciliation, and provide license position reports, at a minimum.
I encourage you to think through your decision and include the main users of the tool and senior management in the evaluation process. I see it so often, where an ITAM tool implementation gets derailed...