Your tamagotchi can live forever, but evenutally around age 10 your tamagotchi will turn into a oldie and the matchmaker will not come, if you mate with a oldie you can get a very special character. Also it is normal to get a 2 year old Tamagotchi Adult.
Well it is normal on the v4. It usually evolve when they are 2 unless you have paused the tama. They will get the matchmaker at the same time as the v3. Usually when they are 7 or 8 years old. I hope I helped. :furawatchi: