Practice with a C or practise with an S—which spelling is correct? In American English, practice is always right. In British English, whether practice or practise is the correct choice depends on its role in the sentence. How can you know which form to use?
In American English, practice may function as a noun or a verb. Regardless of its role in the sentence, the correct spelling is always practice with a C. In British and other non-American versions of English, spelling may vary depending on the function of the word. For example, if you are referring to what a doctor does, you would say that he practises medicine. You spell the verb form, practise, with an S. However, if you are referring to the the doctor’s business, you can use the noun form, practice with a C. Nevertheless, language is always changing. In some forms of English, such as Canadian English, practice with a C is becoming more popular for nouns and verbs. Some examples may help you visualize the point.
Take note of these interesting instances of practice and practise from literature and the media.
Which spelling is correct—practice with a C or practise with an S? In American English, practice is always correct. However, in other varieties of English, you’ve learned that the answer isn’t as simple because you have to take into consideration whether the word is functioning as a verb or a noun. Besides spelling, have you ever wondered how American English differs from the English spoken in the United Kingdom?
from Grammarly Blog https://www.grammarly.com/blog/practice-practise/