This program is Freemium. In the 1990-2000s, programs distributed under the terms "freemium", as a rule, belonged to the shareware group. Only in 2010, "freemium" began to be allocated to a separate class of software.
The difference between the versions in the output on the printout of the text that is printed in the free version. The cost of Premium for the year 5.99$.
Free features of the program remain so. New will be either immediately paid or will please you free of charge. You can donate for development by buying a premium for 1 month.