LMC has supplied Mortons for around 15 years and, in 2004, it moved onto the same site in Horncastle, Lincolnshire.
The mailing company will continue to operate as an independent business and its services will still be available to third parties, Mortons said.
LMC had been owned by Robin and Robert Wilmshurst – a father and son team, however the pair decided to sell when Robin wanted to retire.
Ian Fisher, managing director at Mortons, said that Robert will join Mortons as part of the investment and will run the mailing service.
"Around 30% of our customers already use LMC, so it gives us increased access to polywrapping and lettering services and we will be taking these out to our other existing customers," he said.
Mortons has a turnover of around £10m and employs 80 staff. LMC turns over around £500,000 and will add 13 staff to Mortons through the deal.
Aviation Classics, British Railways and Classic Dirt Bike number among the titles printed at Mortons.