The "Level" of your license limits IO tags. IO Tags exchange data with the field automation devices (reads and writes). The IO Tag count is limited by the Hardkey and matching Software License file.
All IO Tags and All Block Parameters are summed to calculate the Tag count.
Note - If two tags read the same address, they count as two tags
For more information on Tag Limits and "Level" of your license please refer to section 1.5.1 License Tag Limits by Part Number.