Is this purchase safe?

Question

Electronic commerce

You need to buy a certain software product for PC using webmoney.
Apparently, the seller (software developer), in response to a payment from the buyer, must provide him with a key for the software, which unlocks its full version.
Given that the developer is a well-known and reputable company:
1. Where is the guarantee that the developer will provide the key to the buyer after he makes a purchase using webmoney?
2. What can the buyer rely on if the developer does not provide him with a key?