Now maybe it's asking alot,
Yes it is. The purchase of a product can be regarded as a contract - agreed upon by both parties. The Purchaser agrees to pay for the product and the Vendor agrees to supply that product to the purchaser. The only conditionals are the restrictions of the Vendor country's Consumer protections and/or warranty obligations under law.
Until the payment for the product is received by the vendor there IS NO CONTRACT OF SALE.
That means if you see a product at a price you like....but for whatever reason you do NOT purchase it then, but in this case take time with the trial first.....when you subsequently find the price is no different...however many days/weeks/months later you are obliged to enter that sales contract at whatever price point currently exists.
The perfect counterpoint to underline this. If the purchase price was initially $10 but subsequently after a trial time it was now $5 would a purchaser demand he MUST receive the product for $10? No, he'd clearly want to go with the current pricing...
Stardock Sales' decision to provide the product to you at the earlier price is definitely outside of their obligations as a vendor, but is more correctly a good-will gesture on their part.
The 'rights of a Consumer' is something everyone should endeavour to educate themselves about as everyone IS a consumer...
Typically there are only relatively minor differences from country to country...