Cannot run trial version

After being frustrated with an old version of Fences some time back, I uninstalled it pretty much immediately. However, I've now come up with some workarounds for the limitations, so reinstalled it to see if they will work before I purchase it (possibly a number of licences). Unfortunately, it tells me that my licence has expired and I need to purchase a new one.

Is there any way around this?

<follow-up> Am going to have a go at the "purge" process I see mentioned elsewhere.