What this order code buys
The Siemens 6ES7997-1DD20-4BA0 is a licensing line item for the PCS 7 Extended Solution Partner program — it covers the fee component, not a physical hardware module. The description reads "SOLUTION PARTNER FEE PCS 7 EXTENDED", so this is the commercial transaction code for the partnership tier, not a field-replaceable unit you'd swap on a rack.
Sourcing runs through the independent distribution channel. The estimated lead time is 1-2 weeks for a quoted order.