I made several unfinished projects in Sony MSP12, but a laptop crash caused me to need a new laptop. I lost the serial key for 12.0, so could i still work on them if i bought a newer version/build of Movie Studio Platinum?
Generally, your projects should open in later versions (without any extras used that are not included later though, read e.g. here). Note though that MAGIX Movie Studio 18 and 2022 versions are based on a different product and a totally different matter. The VEGAS Movie Studio product line has been discontinued and is not available to buy from the manufacturer any more.