Free vs. Pay versions?

I got the Free version, liked it, then purchased the Pay version ($1.99) only to find the Free version has a $0.99 option to remove ads. The other options are the same price whether purchased in Free or Pay version. So, why $1.00 difference in the two ad-removed versions? And what other differences are there in the two? I’m using an iPhone 6S+ and a McBook Pro Retina - and the system works GREAT. The yet-to-be-unlocked buttons are currently in the way, but I’d be willing to get them if I figure out what’s going on in the pay system. Also have to test with my work PC running XP.

yesmuseum.org about Remote Mouse