You do not have access to this package of the add-on

Why i get this error 

You do not have access to this package of the add-on

See if your 12 months of free updates that were included with your purchase has expired.

yes the free updates are expired

Does this mean you have to buy the paid add-on's again every year?

If I had 3 add-on's that were $49.99 each, I'd have to pay $150 each year after to use the 3 of them?

You can use a purchased addon for as long as you like. The period of free updates after purchase is up to each and every addon maker themselves to set.

I am working on a renewal service that will offer extending the period of service updates for more than 12 or 24 months for a lesser cost. Users with expired addons will initially be offered the same option. Work load is what's delaying the process.

You will find that other platforms use monthly charge for same features. Example 9.95 a month for a Stripe implementation for 36 months would be 358,20. That makes your 150 sound awesome. 🙂

If you don't update Litecart to newer version and stay on the version you started with those 3 add-ons, and don't want update the mods, do they quit working after the 12 month period?

Or do they continue working for years?

They continue for years. As you purchased them.
We don't have subscription services to offer yet.