The program license is a unlimited. All updates (removing errors noticed and introducing new functions) are free for the entire lifetime of the program. The ABC variant (as the only one) can be sold with a license valid one-year.
Time-limited license (valid: 1 year + 1 day) applies only to the program in the ABC variant.
The extension of the license for the following year is equivalent to the Customer buying an unlimited license for the program in the ABC variant (the cost of buying an unlimited license is reduced by the cost of acquiring 1-year license).
The cost of buying a 1-year license is not taken into account when buying variants other than the ABC variant.
The educational license is sold only in the ABC variant. The education license is an unlimited license. The license allows installation on all computers in one classroom (up to 25) and on home computers belonging to teachers.