New South Wales licences and protection
All frogs (and tadpoles) are protected in NSW under the National Parks and Wildlife Act, and it is against the law to take them from the wild to keep as pets. You can get a licence from the NPWS to keep frogs, but you must obtain the frogs from a licensed breeder or society. You can only keep frogs that have either been bred in captivity or for other reasons cannot be released back into the wild.
For educational purposes, schools in NSW have been licensed to enable children and their teachers to collect and keep a maximum of 20 tadpoles to watch them grow and transform into froglets. Tadpoles must never be collected from national parks or other reserves. Once tadpoles have transformed into froglets, they must be released back in the location where they were collected.
Commercial trade in frogs is prohibited in NSW. If you purchase an animal from an interstate dealers, or from anyone else in another state, you must already hold a NSW amphibian keeper's licence and you must obtain an interstate import licence from the NPWS before you can legally bring it into NSW.
You can find this information easily on the New South Wales National Parks and Wildlife site where the laws are fully explained and application forms are available.