这是什么意思呢，升级购买PT的问题？
Pro Tools Ultimate
$499.00 Pro Tools Ultimate Annual Perpetual Upgrade & Support Plan - GET CURRENT
Buy now
Continue to get new features and support
Pro Tools Ultimate (Pro Tools Flex)
$999.00 1-Year Subscription, Paid Upfront
Buy now
Step up to maximum track counts, performance, and surround sound!OR, for purchases made through your Avid Reseller:这两种什么区别？
$499.00 Pro Tools Ultimate Annual Perpetual Upgrade & Support Plan - GET CURRENT
Buy now
Continue to get new features and support
Pro Tools Ultimate (Pro Tools Flex)
$999.00 1-Year Subscription, Paid Upfront
Buy now
Step up to maximum track counts, performance, and surround sound!OR, for purchases made through your Avid Reseller:这两种什么区别？
