You sure you don't have multiple copies of Lightroom laying around...like maybe an older beta version?Otherwise, if you want help, help yourself by providing basic troubleshooting info.
Now I must report that all of a sudden (today) I received the same message.Your Beta Version has expired.This is even though I have a PAID VERSION with a serial number.Their must be some sort of major bug in this program.
Three friends, all with authentic copies & registrations, report the same as of last weekend.