Possible to upgrate SQL Server 2012 express to 2012 Standard? I need to do an in place upgrade of SQL server 2012 express to standard without losing any data. Is this possible? Is it as simple as just running the setup for the standard version? TIA
Yes it's as simple as running the setup and execute the edition upgrade. 

Just in case it's better to backup your database before but everything should be ok.

Details here : 
https://msdn.microsoft.com/en-us/library/cc707783.aspx

Of course, you should buy the standard licence.