Both locals and visiting anglers may buy their fishing license at one of the license salesmen at Norwegian side. Visiting anglers that are buying license for the border stretch at internet must visit a compay to disinfect their equipment and activate their license. It is also possible to do this at several Finnish companies (se list below the map).
You can buy a fishing license at:
1) Karasjok camping (tlf +47 97 07 22 25)
2) Sport 1, Karasjok (tlf +47 78 46 71 00), Opening hours: Monday-Friday: 09:30-16:30, Saturday: 10:00-15:00
3) AE Tapio, Sirma (tlf +47 97 62 47 85), Opening hours: Monday-Friday: 10:00-16:30, Saturday: 10:00-14:30
4) Tana Familiecamping, Skiippagurra (tlf +47 78 92 86 30)
5) Elva Hotel, Tana bru (tlf +47 78 92 82 22)
6) Rustefjelbma servicesenter (tlf +47 78 92 70 44)
You may buy or activate your license at following location at Finnish side of the river Tana:
7) Tenon Tunturituvat, Tanssjoki tlf +358 (0) 400 167 521
8) Lomakylä Valle, Utsjoki tlf +358 (0) 400 948 210
9) Tenon Lohituvat Utsjoki/Niemelä tlf +358 (0) 405 879 097
10) Vetsikon Leirntämökit, Vetsikko tlf +358 (0) 400 617 016
11) Vetsituvat, Vetsikko tlf +358 (0) 440 678 805
12) Tenon Lohiranta, Niittyranta tlf +358 (0) 406 715 800
13) Nuorgamin Lomakeskus, Nuorgam tlf +358 (0) 400 294 669

Map of the Tana water course with local businesses where you can buy Norwegian fishing licenses are tagged.
You can desinfect your ecuipment at the same localities as you buy your license
Remember that the fishing license is valid only as long as you carry proper identification.