Yes you must show "prayer times provided by MuslimSalat.com" or "powered by MuslimSalat.com" which is easily visible to an eye.
You should also put "powered by MuslimSalat.com" directly below or above the prayer times.
See the Muslim Salat API documentation for examples and details.
There are no usage limits when using the Muslim Salat API request, as long as the service is not being abused.
As long as your site is generally accessible to consumers without charge, you may use the Muslim Salat API. For example, if your website is supported by advertising, it likely falls within the Muslim Salat API Terms of Service.
However, not all commercial uses are allowed. For example, if your site meets any of the following criteria you must purchase the Muslim Salat API for a Business license:
Remember, Muslim Salat reserves the right to suspend or terminate your use of the Muslim Salat API at any time.
Yes, the Muslim Salat API can now be used in Desktop applications, provided that they adhere to the other restrictions of the Terms of Service. Note that in order for a desktop application to be deemed "publicly accessible", there must be a publicly accessible webpage from which it can be downloaded.
Please port your question in the contact us page and we will get back to you as soon as we can.