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I only seem to have version 1.5 also, but it runs just fine on my computers with Tiger... Have you tried it?
 
I run v1.5.1 on Leopard and it definitely doesn’t work in Tiger. @Slix can you share your copy?

I bought my license back at v1.0 but never stepped up to v2 or later. However I only kept a zip of the last PowerPC version in my software archives.
 
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