You can claim a free package from your shop page once every 20 hours. You can navigate across various shop sections to find the package you can claim today.
Other than that, every offer you purchase triggers a Free sale on your shop page. The higher the price of the purchased offer, the higher the value of the Free Sale.
Each purchased offer triggers a free sale, except for Premium. Moreover, free sales have to be claimed after every purchase individually, e.g., if you make one purchase but forget to collect the free sale for it, then upon the second purchase, you will only be able to collect the free sale for the second purchase.