How long does AppleCare last after day of purchase?

When you buy the extended AppleCare coverage isn't the starting point. Such as, you buy it after owning the device for 11 months. That doesn't doesn't extend the coverage out to 3 years, 11 months.

The coverage is always based on the purchase date of the device. So no matter when you purchase AppleCare, the coverage is still 3 years total from the date of purchase.

How soon you have to purchase it depends on the device.

Standard AppleCare gives you 90 days of telephone support and one year of warranty coverage from the date you purchase the iPhone. If you purchase AppleCare + within 60 days this extends your coverage by one year (for a total of 2 years) for both telephone support and warranty coverage and covers 2 instances of accidental damage after paying a deductible.

You can also now opt for theft and loss coverage for an additional fee.

Hello,

You can buy an AppleCare+ coverage as a 2-year, fixed-term plan or as a monthly plan that will automatically renew until cancelled. You have up to 60 days after your iPhone purchase to buy AppleCare+. (The monthly plan is subject to country availability.)

You can get the latest information about AppleCare+ for iPhone here: AppleCare Products - iPhone - Apple

Take care!

1 year and it can be extended to 3 years with Apple Care Plus:

AppleCare+ - Mac - Apple