The verb pay is never followed by a direct object that refers to the thing you are buying. We pay for a product or service:
✗ Credit cards are used to pay the product you purchased without using cash.
✓ Credit cards are used to pay for the product you purchased without using cash.
✗ At that time, very few people could pay a university education.
✓ At that time, very few people could pay for a university education.
You can also use pay in these patterns:
▪ pay someone for something
▪ pay an amount of money for something
▪ pay someone an amount of money for something
It was rumoured that Texaco had paid the government over $800 million for drilling rights.
Have you paid your brother for the cinema tickets?
However, pay can be used with a direct object which refers to money that is paid for a specific purpose. The nouns most frequently used in this pattern are:
bill, charge, compensation, debt, fine, price, fee, rent, salary, tax, wage
Around one third of schoolchildren failed to enrol this year because their parents could not pay the school fees.
Married couples are taxed independently, and each spouse is responsible for paying tax on his/her own income.