How can I find the PSoC Creator version that was used to build the project the last time?
Open the .cyprj file as a text file. You will see the last version of the tool used to generate the configuration for the project in the following format:
<component_generation v="PSoC Creator 1.0 Production" />.
The <project>.cyprj file is located under the <project>.cydsn folder.
For example, for the project abc, abc.cyprj file will be located under folder abc.cydsn.