Hello Mario
YES, P&E USB Multilink Universal will allow you to perform in circuit USB flash programming of the MKL25Z128VLK4 MCU.
Then this is just the question of the quantity of pieces that you would like to program and the accessibility/flexibility of the tool.
Less than 1000pcs to program UMultilink is the right tool and Umultilink FX would be faster which is insteresting for high memory sizes.
More than 1000pcs to program in a classical factory assembly chain, it would be recommanded to choose a standalone flash programming tool, embedding its own memory or an sd-card port to store the project code (no computer needed) and a simple button to push to avoid handling errors.
Please find below a long list of Programming tools from 3rd parts vendors compatible with Freescale MCUs
Hardware Debuggers and Programming Interfaces
PS : Unofficially, FRDM-KL25Z can be reused for in-circuit USB Flash Programming.
You just need to buy and solder connectors J11 and J6 and acquire a JTAG/SWD cable :smileywink: