Hi Piotr, you only need the activation code if you buy the software. The free version allows you to design in full.
Please note though that since you were last a full member with us, we no longer offer the StairFile Lite service. You need to buy a StairFile here to receive your manufacturing files (also included is a review and revision of your project): https://wooddesigner.org/membe…..discounts/
EDIT: Premium Support now includes the StairFile service free of charge (minus the formal review – this is now an optional extra).