I have purchased an Avast! 4 Professional Editon on Feb 2, 2006 for a one-year license. It was purchased through the distributor of the product, ShareIt!. ShareIt has confirmed my purchase of the product. The expense has appeared on my credit card bill.
Avast has sent me a message indicating my license has expired. ShareIt! is not claiming any responsibility, only to contact this forum. And I am left without the use of the product. Anyone out here having similar problems with either Avast or ShareIt.
This may be co-incidental that this is around 60 days, did you first use the Pro trial version and did you enter the registration key you received from Share*It ?
Aside from checking the registration information as ardvark mentions, check your system date, especially the month and year.