Reversing Key using pattern

I have decoded 3 feature keys using patterns alone. It's not very complex, but now it's a pain for the feature I'm working on now.

As an example I have provided 3 legitimate codes used to reverse the pattern.

System Serial# = 50000, Legitimate license code = aMrNvhKz6pR3
System Serial# = 50217, Legitimate license code = aMvRwDKzEhO3
System Serial# = 65218, Legitimate license code = MAzPvwoNMlR-

Now let's pick a random serial number between 50000 & 65000: 54222

Here is this features reversal to get to generate the licensed code.

1st digit in serial number determines 1st digit in licensed code:

5xxxx = a
6xxxx = M


2nd digit of Licensed code is determined by the 1st 2 digits in serial Number:

50xxx = M
51xxx = 6
52xxx = U
53xxx = E
54xxx = Q
55xxx = A
56xxx = Y
57xxx = I
58xxx = unknown - no data
59xxx = 8

60xxx = M
61xxx = 6
62xxx = U
63xxx = E
64xxx = Q
65xxx = A


3rd digit of serial# (only) determines 3rd digit in licensed code

xx0xx r
xx1xx z
xx2xx v
xx3xx 3
xx4xx t
xx5xx 1
xx6xx x
xx7xx 5
xx8xx q
xx9xx y


4th digit of serial# (only) determines 4th digit in licensed code

xxx0x = N
xxx1x = R
xxx2x = P
xxx3x = T
xxx4x = M
xxx5x = Q
xxx6x = O
xxx7x = S
xxx8x = N
xxx9x = R


5th digit of serial# (only) determines 5th digit in licensed code

xxxx0 = v
xxxx1 = x
xxxx2 = u
xxxx3 = w
xxxx4 = v
xxxx5 = x
xxxx6 = u
xxxx7 = w
xxxx8 = v
xxxx9 = x


For 6th digit of license code, use chart below:

If serial# starts with 5, use:

Look at last number (of serial) and match with chart:

0 = h
1 = h
2 = h
3 = h
4 = D
5 = D
6 = D
7 = D
8 = x
9 = x

If serial# starts with 6, use:

Look at the last number (of serial) and match with chart:

0 = g
1 = g
2 = g
3 = g
4 = C
5 = C
6 = C
7 = C
8 = w
9 = w


For 7th digit of license code, use chart below:

If serial# starts with 5, 7th pos = K
If serial# starts with 6, 7th pos = o



For 8th digit of license code, use chart below:

Look at last 4 of serial# (ignore the last 3). Using the first number, use the chart below:

0xxx = z
1xxx = V
2xxx = j
3xxx = F
4xxx = r
5xxx = N
6xxx = b
7xxx = 7
8xxx = unknown - no data
9xxx = Z



For 9th digit of license code, use chart below:

Look at last 3 of serial# (ignore the last 2). Using the first number, use the chart below:

0xx = 6
1xx = M
2xx = E
3xx = U
4xx = A
5xx = Q
6xx = I
7xx = Y
8xx = 8
9xx = O


For 10th digit of license code:

Look @ last 2 digits of serial#. Use the chart as follows for 10th digit:

00-09 = p
10-19 = h
20-29 = l
30-39 = d
40-49 = n
50-59 = f
60-69 = j
70-79 = b
80-89 = o
90-99 = g



For License positions 11 + 12, use the following:

If serial Number starts with 5

ends in 0: R3
ends in 1: N3
ends in 2: T3
ends in 3: P3
ends in 4: Q3
ends in 5: M3
ends in 6: S3
ends in 7: O3
ends in 8: RZ
ends in 9: NZ

If serial Number starts with 6

ends in 0: R4
ends in 1: N4
ends in 2: T4
ends in 3: P4
ends in 4: Q4
ends in 5: M4
ends in 6: S4
ends in 7: O4
ends in 8: R-
ends in 9: N-


The generated license code is: aQvPuhKrElT3

I looks like basic look-up and arithmetic. The program is however changing the algorithm so you can't repeat for each feature.

I was hoping for a Uber secret program to help out. To save time of course.