Considering that you did have access to the game you purchased approximately 2 years before it was made F2P, the value would have been in playing it, i.e. the chance at playing the game for all those months before any F2P players. If by personal preference you decided to not play, does not mean the value of accessing the game was not there. It is not uncommon for publishers to make certain games or parts of a game F2P after the said content is being phased out to pave way for new updates/products. Those who opt not to play, having owned the product before they were made F2P do not get compensation for time not spent while the product was still paid content. Like you said, it is very likely that you won't get a refund for content purchased in 2017. However, that would be something up to the retailer you purchased from, subject to their refund policy.