Use the main menu > GPS > Display GPS ID command.
Mapwel displays GPS ID in a specific way, with checksum of all previous digits.
For example ID 32043123 is displayed as 32043123_18 where 18 is 3+2+0+4+3+1+2+3. The checksum helps to avoid typographical errors in GPS ID when purchasing Mapwel license. Please note that checksum does not change if zero digit is omitted. This is the most frequent typo error.