This kind of gift is subject to some conditions, which is his saying: If you like this program then you can donate to the programmer. This condition clearly shows that this is not a sale, because the word donation means that the owner or programmer is not stipulating that the user of the program should pay a specific amount in return for using it. 

Based on this, this condition makes this transaction a gift. 

A gift may become a sale if the giver stipulates that the recipient has to give him a certain amount of money, for example, in return for the gift. 

Ibn Qudaamah said in al-Mughni (5/398): If a specific reward is stipulated in return for the gift, that is valid, as was stated by Ahmad, and it comes under the same ruling as sales. End quote. 

Thus it is clear that there is nothing wrong with using this program, without paying anything, and that is not an invalid transaction, and it is not like taking people’s money by means of embarrassment, because there is no room for embarrassment or shyness here. The owner of the program cannot see the user and he does not know him, so it cannot be imagined that he would feel embarrassed before him.  

And Allaah knows best.